Exactly...you'll never really know...I've see pit/lab mixes that look almost full pit..just not quite right....you mix a pit with another bully breed...say, american bulldog...and you pretty much can't tell unless they get too big.
Kiwi is Pit bull x sharpei
can't see
all the extra skin and the curly tail in this pic...but they are there. she has typical sharpei coat color. Her ear set is very sharpei too. She is mostly Pittie tho so I refer to her as such, as even other pit owners don't see the mix and often ask me if she is purebred. I actually went to the shelter hoping for a sharpei mix but wasn't opposed to a pit (she was listed on petfinder as a sharpei mix). Best of both worlds IMO.