Trusting the person who cleaned the chitterlings is very important. Care must be taken when preparing chitterlings, due to the possibility of disease being spread when they have not been cleaned or cooked properly. These diseases and bacteria include E. coli and Yersinia enterocolitica, as well as Salmonella.
The chitterlings are turned inside out, cleaned and boiled, sometimes in baking soda, and the water is discarded. The chitterlings can then be used in a recipe.
A common practice is to place a halved onion in the pot to mitigate what many regard as a pungent, very unpleasant odor that can be particularly strong when the chitterlings begin to cook.
Common serving technique is with a vinegar based hot sauce and BBQ sauce. The vinegar odor and taste will disguise any remaining odor from the chitterlings.
Personally, I don't eat them. There are too many other foods available to resort to eating a pigs poop chute IMHO.
The risks outweigh the benefits, again, IMHO.