"As to Spock's cabin in "Amok Time" - there is room for a small toilet room next to the spinning mirror/cabinet."
Hmm...maybe a part of the spinning cabinet has a toilet seat.
One third is mirror section with the drawers, one third is a closed wall, the last third is unknown (maybe Spock felt in "The Conscience of the King" that the toilet section wasn't the part where the phaser on overload could have possibly
It's really stupid that starting with Season Two they didn't put the "bathroom door" on the opposite side of the quarters set. It somehow looks odd that all the quarters have one adjacent room with a yellow door to the left that doesn't appear to be connected with the quarters. Maybe it's an ultrasonic shower cabin most officers have to share (Kirk and McCoy probably didn't give up their 'Hilton suites' on Deck 12 without a fight