All %^&$ (crap) aside, it sounds like it could be a faulty wax ring. Less likely is cracked pipe. Toilets have internal traps that prevent gas from coming though. Unless you have a gurguling toilet.

Thanks for the laughs! Who said Plumbing can't be a laugh! HA HA HA!

: : I have a fowl smell coming from my bathroom. I believe that it is coming from the toilet. I have cleaned the toilet and that doesn't seem to help. If my main drain line is dirty/clogged, can the smell come up through the toilet bowl? If not, maybe the smell is coming from the base of the toilet and I need a new o-ring?
: If its FOWL smell look for a Chicken or a Turkey in pipe..... hic...If its a FOUL smell, yes it could be from a faulty wax seal at the toilet base. hic