There is another thread about that very thing.  Search for pictures.  I think it was in this forum.
If she is a well reviewed provider, I would not be too concerned, but if she has few or no reviews, don't do it.  If she has any reviews, you might PM some of her clients and ask them about it.

Swim

hi

being a provider myself, i have never asked for a pic of my client. I have no clue as to why she would ask except for the fact she might have had a problem with a previous client and a pic would promise it not to be him.

bridgette

I would never ask a potential client to send a piture of himself. I am much more concerned about personality than looks.
A few men have sent pictures along with their appointment request. If those pictures  include any nudity they get deleted and no appointment.

I've heard of it but it's certainly rare.

She may have preferences that she just does not click with...  if you don't look like her ex, you're in.
skb

the Post Office, 3rd picture down, 2nd row from the left. No one ever asked for a picture after that.

She may not want to see certain races, and this is her way of screening. This board has a long history of posts by minority clients and there inability to see certain providers.