I think it depends on the trainer.
I go to a gym where there is a female tool personal trainer. Yes, she's ripped, cut, solid, little to no body fat and therein is the problem. She knows it.
I watched this PT "work" with a heavy lady client one evening and it totally disgusted me.
She spent more time in front of the mirror watching her own a$$ flex than pay attention to her client. :SaiyanSmilie_anim:
I SOOOOO wanted to tell the client to ask for someone else. I really felt bad for her..
My trainer, FF, has a different mindset. We use the mirrors to check form and technique - for both of us. I watch him and he watches me to make sure I'm following his lead and getting the movement right.
Used for the right reason, mirrors are good. Butt (ha!) if all they are going to do is allow your to admire him or herself... he/she needs to go the F home and do that on his/her own dime and not waste your time or money.
ok there... my 2 cents... LOL