I would be no more likely to let a sex worker have my photo than I would to let her have my bank account details or passport number. As Dani said in a earlier post on this thread, there is a risk of the photo being misused, possibly for blackmail.
And one question. What if you send a photo of somebody else? Does she compare the photo with the reality, say "this isn't you" and refuse to see you? What if you send her a photo that looks like a down and out, and turn up looking seriously wealthy? (An interesting experiment, that.)