Had that experience as well.
Visiting Austin for a business trip and found a provider on TER who's reviews looked really good. Right skills, attitudes, services and rates - it all lined up. Called her in the morning for an afternoon meeting and the phone was answered by a different provider who said she was covering for her friend who was on travel with her family.
She offered to cover the session for the same rate. I asked her for her TER and ID and looked her up. It all looked good. In fact he "normal" rate was $150 higher than her friends. So I called back and we set the time and place.
When I got to the door I was met by a late 20-ish blonde with an amazingly warm smile. I returned her smile and then looked down and I'm sure my smile flipped into a scowl. She had a very cute and a slim body - except for the giant bun in the oven! She kind of smirked at me and said, "Oh, you didn't know, did you?" She had actually posted recent pics on her BP ad, but I had not bothered to look at it and it wasn't mentioned in her recent TER reviews.
Still fucked her, 'cause.... why not? BBBJ, CG, RCG, more BBBJ and a HJ w/facial finish.
But would not deliberately look to book and pregnant provider going forward.