although many cleaning solutions are ammonia based, it wouldn't be the ammonia that would case me to be concerned. Most cleaning solutions also have a fair amount of alcohol. THis is what causes it to evaporate quickly for "less streaking". That, the perfumes and dyes would be more concern to me than the amount of ammonia, as ammonia is a natural part of an aquarium. Some cleaning solutions have more chemicals than others. I use, and have used, windex (Basic type, often no-name brands even) to clean my tanks for many many years and have never had "sudden death" after cleaning my tanks. That is NOT to say it can't kill them, I would imagine that if the inhabitants were already weakend through something else, or were extremely senstaive (such as an earlier poster commented on a fry tank) then a small amount of cleaning solution in the water could perhaps cause a problem, but unless you spilled a fair amount into the water, I wouldn't worry about using windex. I will comment that when cleaning, I take extra caution to not let the spray go over the tank.. just to be careful.
And ni regards to glass... I've never heard of glass "breathing" or that it was porus. If I remember correctly, I thought glass actually WAS a liquid. As could be demonstrated in very old windows you could see the glass, over many many years, actually sags. *shrug*