How authentic is Osho-style tantra?

I've just come off a beginner's introductory tantra weekend. Most of the activities were so-called active meditations and exercises from the Osho -cult (Rajneesh'ism). However despite what the instructor said many of us had great difficulty in rationalising these somewhat weird acticities with what we understood as tantra. So exactly just how authentic is Osho-style tantra? Most of the so-called tantra schools in the UK are 'contaminated' with Osho. So when schools advertise as offering tantra courses (at ever increasing levels and prices) and then offer stuff from Osho I guess this is tantamount to fraud?