I'm with all you guys on this one. I always douche, Hell I do a lite douche almost every day before I go to work. Not for sex just to be extra clean.
For sex though I do a complete clean out for sure specially if its planned. If its impromptu I tell the guy, I have to shower first and most are cool with that and will wait a short amount of time, from my expiereience. If I happen to run into issues while cleaning out I get out of the shower and tell him things are not going well and we can do it another time or he can wait a bit longer for me to get things under control.
I've also done the Immodium thing once or twice too after a good clean out. But like others have said accidents do happen and sometimes its just extra water that hasn't been gotten out and other times its shit. Take each situation as it comes. If you stick your dick in and you smell shit right away you know the bottom didn't bother to douche. When I topped it was an instant mood killer and I was done.