Licking inside of lip

Recently while I’ve been hanging out with my rats, one has been trying to lip the inside of my lip by pulling it down. Sometimes she scratched the inside in the process. I’ve heard rats like blood so is that why?

Looks like you have a rotodentist or whatever you call them. Alot of rats like to clean teeth and many people let them into their mouths to do that. I am NOT one of those people! I actually find it a bit gross... Your rat is being very affectionate in that video and if your lip is bleeding it is most likely from long/sharp nails. Rats DO NOT like blood, so whoever told you that is completely wrong.

a rodentrist she wants to clean your teeth
(likely she thinks you have some good food in your mouth)
she is treating you like family
some rats like to lick your teeth etc ….. and as previously stated, rats do not like blood

not a good idea to allow it because your germs might make her ill

That's sweet! I've had plenty try to do that but I don't let them, we have so much bacteria in our mouths!