How can you identify a crystal meth user?

Question by Vanessa P: How can you identify a crystal meth user?
I think my roommate may be using it but I’m not sure. I found a waterbottle with a hollowed out pen shoved through it in her fridge. What does it look like and smell like?
She isn’t in a chemistry class.
Over how long of a period would it take to rot her teeth?

Best answer:

Answer by Tuan Nguyen
she could be doing an experimentation for chemistry class?

update: LOL, maybe learning chemistry as an extracurricular activity on the side?

Know better? Leave your own answer in the comments!