It isn't that common in my experience, but it does happen. Never bothers me if it is discreet (i.e. Using punting phone or AW email), as long as they are not overtly touting themselves ("I'm doing a special offer this week babe") and as long as the message seems specific to me rather than something sent to a huge mailing list (which a girl in Manchester who I saw years ago openly admitted to using).
Assuming all the above, the only note of caution for me is that sometimes I think the girls who do this may see you as a bit of a soft touch, and they won't try as hard for future meetings as they did for the first meeting. I had this with one particular girl who I got on well with, she got into the habit of texting me when she saw I had a reverse booking posted. The first couple of times we met were good, the third was OK and the fourth (and last) was frankly disappointing. It began to feel to me as though she couldn't be bothered any more. She disappeared from AW shortly after that last meeting, so maybe I was right.
