My Chico used to give us a hard"love-Bite"sometimes when he's being cuddled and yes it hurts
But now we can see it coming and a very firm NO CHICO! stops him in his tracks,but he's old enough to know when he's in trouble and seems to understand NO!...A playful kitten is another story,it's very tempting to play with a kitten with your hands,I have the scars to prove it,but it's better for the kitten if you play with a toy,rather than your hands,that way he'll not think it's ok to bite the hand that feeds you..
Moving feet and arms in bed is a very popular target for kittens,something they usually grow out of though. IMO