Lenny bit me once, was a newbie mistake from my part, but it was like a bird bite. It didn't cut me, just pinched pretty hard. Never happened since (cuz it tought me a lesson on how to approach him). And now he's pretty docile for a veiled. But I've read on this forum that some people bled from a cham bite.
Fractal bit me twice and it was a solid pinch. He doesn't bite now because he's afraid I'll put antibiotics in his mouth. I feel lucky he needed them when he did and got trained. lol But if I approached him too fast or carelessly, he could learn biting does work for him again. His mouth is bigger now too.
I've been bitten once by my veiled. It felt like a really bad pinch, but did not draw blood. He got startled when I was holding him and flared and struck out at the first thing he saw, which happened to be my thumb. He has not bitten me since.