Plugging 30A 5th wheel into 50A service

The original question was can I plug a 30 amp RV into a 50 amp outlet, the answer was yes with an adaptor! Someone, mentioned that, that was dangerous, it is not, in fact several posts indicated that is was less likely to have a problem, brownouts, triped circuit breakers, etc by plugging into the 50 amp outlet, too which I agreed. At least one person disagreed and went into an esoteric discussion on wiring, and that it was the same regardless of which plug was used. I disagreed and continue to disagree! A "50 amp" plug is actually 100 amps total, that is two 120 volt 50 amp feeds with a common neutral. You can get real close to overloading a 30 amp circuit, but you have more cushion, with a 50 in a rig designed for 30 amp service. If there is a problem, your main circuit breaker in the rig would blow long before your pedistal breaker would go, and no you can not draw more than the maximum of 30 amps, and in a 30 amp rig with adaptor there is no way of seeing 240 volts in your rig! Even in a 50 amp rig, 240 volts to your equipment would be unlikely due to the fourth lead, ie ground!