I would say not ALL turbo regals leak BUT I would venture to guess that most (if not all) running high boost levels do. Maybe not bad leakage but some seepage at the very least.
Basically it goes this way...in a normally asperated engine the crank case is under a vacuum, when you start running any kind of boost (especially higher levels) the case becomes pressurized.
On our Blown alcohol funny car, we have constant seepage and have to change the oil every few runs because of the fuel deluting the oil. We're running TONS of boost (50% - 70% overdrive on a 10:71 blower) and it has a tedency to force things where they normally don't go.
A dripping leak would signify a problem, a seeping leak, I would think, would be normal...depending on your boost levels.