Personally, I think that even though Donald is not smart enough to be president, he is smart enough to realize that there is no way to buy the kind of publicity he'll get by toying with the idea of running for president. He may not know what the country needs but he does seem to know what the media needs.
Donald Trump is, as a candidate, the opposite of Ron Paul. Paul has created and popularized a set of policies that have little to do with the real world; Trump has created and popularized a personal image that has little to do with the real world.
Donald challenges Obama's proof that he was born in the US. This strikes me as a serious issue. About as serious as Donald's failure to provide any certificates proving that that is really his hair.