No they are not using any numbing , stay-hard cream, the reason being they want you to nut fast, and get the hell out of there, after you leave you money of course. They use massage oil, baby oil, and other lotions for 'happy endings.'
You would know if they were using that numbing creme on you as it sometimes feels like novacaine, well it did for me anyway. One time I tried a condom with numbing cream in it and tested it out on my wife. Fuck my dick just died, and went limp, and I couldn't fuck anymore, but that's on my wife, as I never tried it out on a working gal. Someguys love the stuff, as it lets them FUCK for 1/2 hour or one hour straight, but it's just not for me.