One of the things that is brought up here is the fact that you cannot predict spoilage. It is regional. It depends upon the temp of your counter, your refridgerator. When it comes to avocado, to me, once you cut it you eat it, period. I don't think it is poisonous, but if it looks bad, it probably is. I only recently learned first hand about having a sniffer gone bad. But if it looks bad, smells bad, throw it away, don't take a chance on it. If you want to keep it for awhile, do as has already been said. Squeeze a lemon or lime over it, and press plastic wrap right over it (right on the guac). You can get a few hours on it. Otherwise, sit down and eat the stuff. I'm lucky (I considered it a curse as a teen), I am tall and large (no, not particularly fat). So I will often take a bite of something I'm about to serve just to make sure. No one has every even gotten an upset tummy from food I've served (well, I have had two diverticular friends who I warned not to eat specific dishes at large parties, but they ignored my warnings; their problem not mine at that point)
Anyway, during the winter I can leave food over-night in my kitchen. During the summer I wouldn't dream of it. Honestly, my kitchen is so cold in the winter that I have to nuke butter to make it spread-able. I've lived many places and in many kinds of homes. There is a lot of variety, so speak to your neighbors and college extension service, and learn what works where you live.