Added - I just realized what your "name" here is - oh my heavens! I wonder if anyone else realized it! You have a funny sense of humor!
Original:
Sounds like you find skid marks in his underwear.
Get some wipes and put them beside the toilet. Tell him to use them. Make SURE these are the kind of wipes that are biodisposable and can be put in the toilet.
Does his rearend ever get sore? My younger son had trouble with that, and he was trying to get clean. He just wasn't getting it "right". He'd clog up the toilet using so much toilet paper. The wipes were my solution, and making him learn how to use a plunger.
When he'd get sore and red, I gave him Desitin. He didn't like having to use it, but it would help. Between these 3 things, he finally learned how to clean properly.
I would not take your son's toys away over this. I would not shame him. I would talk to him about smells and stains and red butts causing itching and that if he scratches and doesn't wash well, and then puts his fingers in his mouth, that he can get very sick.
Good luck,
Dawn