Am I the only one that likes a high class date in a total dump motel? Brings out the nasty!
I've done a bit of light negotiation for multiple hour/multiple girl services, but isn't really the norm. I have suggested prices if a particular rate was not offered up in the ad.
Double checking prices, I pretty much always do that with someone new. And I usually confirm if I am receiving a grandfather rate.
At the end of the day, I try not to start the "working relationship" on the foot of trying to save $50. That being said, I have been able to afford to be off Backpage (or Craigslist in its glory days) for a while. When I was on there, I was counting my pennies.
As for overcharging? Well for $750 for 2 hours I would expect gorgeous, flawless body, full PSE up for doing pretty much anything, flawless DD jugs, a fantasy girl persona, and outcall to my house where I can enjoy myself with the pleasures of home.
...but sometimes you just need to drop the cash to kill the curiosity.