Yes, its a good idea to ask if they are cleaned out unless you want shit all over your dick. Another thing to consider is getting an infection due to some of the shit getting into your dick if your topping, it will have you pissing razors in no time. The bottom should have a good understanding of their need to clean out. As a bottom I focus on my diet heavily, little meat lots of greens, but I make sure my top will not be grossed out and flush for until it comes out nearly clear. Bottoms should also consider popping an imodium AD just to make sure there are no issues later in the evening after an 8 hour gang fuck in the sling at the local bathhouse.