Not really, remember that negative modifiers still apply to the check. Even with glibness, you can't just enter a room and claim to be the king. Anything that would be really abusive, such as the King, or getting someone to do something for you that might very well end in their death is still at a -20 to the check, so with Glibness on it's only a +10, and that's without the GM ruling the dificulties as being higher.