I'll pretty much go with the guys who already responded. I take "flat rate" to mean that this is the rate I charge, with no upselling, for the hour (or half hour), for the services listed or implied in the ad. Some of these ladies have a sliding scale based on various services such as L1, L2, L3, L3+G, etc., and they attach various rates. If it's outcall, I understand it to mean no trip charge, driver fee, etc., etc.
Jade is one who often includes this wording in her ads such as this one:
http://www.eccie.net/showthread.php?...ight=flat+rate
It's probably overkill and redundant but no big deal. Just underscores she has a single rate and it covers all the usual stuff.
As to Slow&Easy's note about "until you pop," I've generally seen wording of "UP TO an hour" being the code phrase for that action. If I see "UP TO" in an ad, I move on.
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