Odo- Quark...I´d say, that was a hate-love relationship (but not in a sexual way).... they did need each other in a way, even they did not really like each other, but to the same time were somewhat fond of each other. Also they would miss each other if one were gone and they did care for each other in a certain way and level too.
As for Slash I too think its out of character for most Star Trek characters... there are a few (like Garak) where it might be in the natur, for most others however it seems not the case.
But what people write when living out there fantasies is up to them. Everyone like he/she wants.
As for reading, I read sometimes Slash pieces, when they are well written, but jump about everything too graphic. When flying over it first I pick out scenes I find ok to read, mostly the scenes that could be interpretated as (close) friendship and show the inner working of a character.
For example the story "Just for a smile" by V. M. is actually a quite heavy Slash story...but the first half is not Slashy at all (well maybe just a very little bit as the first half goes on on Garaks part, which is all right...its Garak...)...so the first half is very nice to read. The second half gets slashier, but first it still all right and there are interessting scenes inside...the last part is heavy slash, that I don´t read. But would I not read the whole story because its slash I certainly would miss out on the 2/3 of the story, that are pretty good.
TerokNor