Initially, Mr. Sleech was thought of to be a mad scientist who works on experiments. However, when Doug meets him he is a very polite and kind man. As it turns out, Mr. Sleech is a baker who works all night and sleeps all day. When he comes home from work, he experiments down in their basement, which he converted to a personal bakery. Mr. Sleech feels as though Al and Moo are embarrassed about having a father whose just a "baker" and not some sort of genius scientist.
Doug invited Mr. Sleech in during his report to hand out donuts to the other students, as a way to break the ice and clear up any confusion they had about him.