Defensive bites from small snakes are painless and the worst thing you can do is react by pulling your hand away as you risk ripping out the snakes teeth, not good for you or the little snake.
Defensive bites even from large snakes are usually painless, you are not sure you have been bitten till you see the blood.
Food response bites are different as they bite hard and hang on usually wrapping coils as well, you will bleed a lot and if you are alone it can be difficult to remove a snake that is in feeding mode and won't let go. long teeth species like GTP's and RSP's are worse as the teeth can go in to the bone and break off, again the worst thing you can do is react by pulling your hand away as you will do serious damage to the snakes teeth and tear your flesh.
Alcohol is the only thing that will get them to release, (wash the snakes mouth and eyes after) keep a bottle of vodka handy. Holding them under water rarely works.
I regularly get bites from hatchlings but just ignore it, never had an infection. No adult bites since I stopped keeping jungles and coastals, use long tongs with GTP's and other aggressive feeders.