How is this even a question worth asking?
When she approaches you, say 'no thank you' and carry on with what you were doing. If she forcibly tries to put it on anyways, move your head out of the way and say 'really, I'd rather not'.
Do not try to explain why you don't want it, just say no and try to move on. If she's a sensible human being, she'll get the message.
If she doesn't get the message after that, then you don't have to be polite anymore, because she stopped being polite too.
