I cannot speak for others, but I don't have a "comet theory". My theory is that we don't know and are making educated guesses. At least some are making educated guesses. Others are making wild speculations that I find mildly entertaining.
Then take the time and do the research learning how transits work.
I am going to take my data and submit it too Super Planet Crash and see if they can make a model out of it.
Here is the data that I have been working on based on the light charts of KIC 8462852.
I was wondering if you could create a base model for star KIC 8462852 using the supplied data?
It would be interesting to see a model of what KIC 8462 might look light with supposed objects orbiting it. Starting with Day Transit Occurred (from zero) then Transit of Object, etc. would correlate to the data  (1)D-140 ,  10-13.62 and so forth across the data sheet.
Data with * indicates a possible planet orbiting KIC 8462 based on the amount of time between each orbit that was based off of the dims having nearly the same dim values as well as associating the orbital period with orbital periods for planets orbiting our Sun.
For example *1 at Day 140 and *1 at Day 259 both have approximately the same data regarding transit time, light dim and a period of time between each observed event of 119 days that would suggest this object is slightly larger than Venus and has an orbit around KIC between Venus and Mercury  with an orbital adjustment based on KIC being 1.5 times larger than Earth based on Kepler's Law.
You will need the Light Chart which I have linked here to compare the data- 
https://www.facebook.com/641915669282915/photos/p.661715923969556/661715923969556/?type=3&theater
Day Transit Occurred (from zero) / Transit of Object  / Orbital Distance from KIC 8462 /   Dim Caused (dim/normalized flux) / Time Between Next Transit /  Possible Size of Object/Possible Orbital Bodies    Notes
*1(1)D-140    10 – 13.62 days    b/tw Earth and Saturn    .0050/.9950    18.65 days    Mars to Earth / 1
*2(2)D-159.02    1 – 2 days    b/tw Mercury and Mars    .0015/.9985    49.94 days    Mercury to Venus 
*2(3)D-208.96    1 – 2 days    b/tw Mercury and Mars    .0015/.9985    45.4 days    Mercury to Venus
*1(4)D-259.02    10 - 13.62 days    b/tw Earth and Saturn    .0050/.9950    22.7 days    Mars to Earth / 1
*2(5)D-281.72    1 – 2 days    b/tw Mercury and Mars    .0015/.9985    72.64 days    Mercury to Venus
*3(6)D-359.02     3 – 4 days    b/tw Earth and Saturn    .0025/.9975    18.16 days    Venus to Mars / 1
*2(7)D-372.64    1 – 2 days     b/tw Mercury and Mars    .0015/.9985    49.94 days    Mercury to Venus 
*2(8)D-427.24    3 – 4 days    b/tw Earth and Saturn    .0022/.9978    18.16 days    Mars to Earth / 1
*2(9)D-445.4     1 – 2 days        + .0022 / + 1.0022    54.48 days        Increase in light emitted from KIC 8462, transits 9,10,12 & 13 are mirrored.
(10)D-500    1 – 2 days    b/tw Mercury and Mars    .0015/.9985    286.26 days    Mercury to Venus
(11)D-586.26    40.86 days    Outside of Solar System    .15/.8500    354.6 days    Jupiter / Many    Jupiter causes a .10/.90 dim, -.05/-.05 difference, Neptune transits at around four days. Transit is 10.25 times slower than Neptune's transit.
(12)D-1140.86    1 – 2 days    b/tw Mercury and Mars    .0015/.9985    31.78 days    Mercury to Venus
(13)D-1172.64    1 – 3 days        + .0022 / + 1.0022    27.24 days        Increase in light emitted from KIC 8462, transits 9,10,12 & 13 are mirrored.
(14)D-1209.08    2 – 4 days    b/tw Mercury and Mars    .0038/.9962    36.32 days    Mars to Earth / 1
(15)D-1240.86    1 – 2 days    b/tw Mercury and Mars    .0017 / .9983    18.16 days    Venus to Mars / 1
(16)D-1259.02    1 – 2 days    b/tw Mercury and Mars    .0015 / .9985    72.64 days    Mercury to Venus
(17)D-1336.32    1 – 2 days     b/tw Mercury and Mars    .0015 / .9985    27.24 days    Mercury to Venus
(18)D-1359.02    1 – 2 days    b/tw Mercury and Mars    .0015 /.9985    13.62 days    Mercury to Venus
(19)D-1372.64    1 – 2 days    b/tw Mercury and Mars    .0015 / .9985    22.7 days    Mercury to Venus
(20)D-1402    1 – 2 days     b/tw Mercury and Mars    .0015 / .9985    27.24 days    Mercury to Venus
(21)D-1417.80     1 – 2 days     b/tw Mercury and Mars    .0015 / .9985    27.24 days    Mercury to Venus
(22)D-1459.02    1 – 2 days     b/tw Mercury and Mars    .0015 / .9985    31.78 days    Mercury to Venus
(23)D-1490.8    6 – 9.08 days    b/tw Earth and Saturn    .0038 / .9962        Mars to Earth / 1
                    
Data added 2.14.16 – Measurements approximate and are based on each 100 day transit being divided up into 1/16th = 5 days, 1/8th = 20 days and an inch = 160 days                    
                    
D(24) – 660    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    25 days    Mercury
D(25) – 690    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    10 days    Mercury    D(25 – 27) all have basically the same transit data
D(26) – 700    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    10 days    Mercury    Possibly a very fast moving object transiting KIC 8462 with an orbit value of 13.333 days around KIC 8462.
D(27) – 710    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    20 days    Mercury
D(28) – 720    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    25 days    Mercury
D(29) – 740    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    20 days    Mercury
D(30) – 765    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    150 days    Mercury
                    
D(31) – 910    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    100 days    Mercury
D(32) – 1010    .5 – 1 day    b/tw Mercury and Sun    .0090/.9910    85.5 days    Mercury
The data is approximate because I do not the Super Micro Enfilbulatory Machine That Goes Ping to zoom in to see the data up close without the data turning in a Super Giant Mega Pixel.
Let's take a look at Jason Wright's theory of a Swarm of Dyson Sphere's.
If there was a single ring around KIC 8462 made of a metal alloy there would be permanent reduction in the light emitted from KIC 8462. Now lets reduce that amount of metal alloy in the ring between the collectors to help save on the metallic alloy resource use and waste. What we might have would be something that looked like this.
------[   ]-------[   ]------[   ]------
The dashed lines, ----- ,would be the connector support truss between each collector, [   ].
With a large collector siphoning off material from KIC 8462, possibly plasma as well as thousands of these collectors orbiting KIC 8462 what would take place is a continual dim in light across the data sheet of KIC 8462 causing a dim of .0001/.9999%, theoretically.
If you look at the light chart of KIC just around the .001 to .0001 dim range there is a consistent pattern of dims and light returning to normal that would suggest that a collector of some sort was in orbit around KIC.
A sun is always turbulent and for any consistent patterns to emerge in data would mean that something artificial is present and causing the consistent pattern on the surface of the sun to take place.
One area that had not been discussed as being possible is that a large planet the size of Jupiter or Planet Nine with a ring system comprised of ice chunks orbiting the planet could be orbiting KIC where every so often a rogue ice chunk comes close enough to be sublimated causing a cometary tail to form that could result in the dim of KIC 8462.
With KIC 8462 being 1.5 times larger than our own Sun the sublimation range would be increased.
The question is could ice chunks in orbit around Jupiter actually be possible or would the ice chunks sublimate into a large cometary tail?
This is the image that I am seeing at KIC 8462 using the Ice Chunk Roadrunner Theory.
The Jupiter sized planet has billions of various sized ice chunks orbiting it. As the planet comes close enough to KIC 8462 the ice chunks closest to KIC 8462 sublimate causing a large cometary cloud to form that would follow the orbit of the Jupiter like planet until the planet orbited far enough away from KIC 8462 for the sublimation to stop.
I will say one thing though. It's not comets, because it's not comets.