Does he get the poo on his fingers when he is at the loo or does he stick his fingers in his jocks?

And has the problem come up at school as well or do you think it may be directed at you?

I suppose what I am asking is does he deliberately get his hands dirty and then smear or are his hands getting dirty as a consequence and then he is just trying to wipe them off on the most convenient thing?

Maybe having some hand wipes about - like wet ones or similar - that he could use to wipe his hands whenever they are dirty.

Sorry that I can't be more help - but I wish you luck.