I can think of a couple people who are probably intps who I know in real life but if they're mature they're about some of the best (and hottest) people I can meet.
That being said, I knew a guy who was (very likely) and intp and he was an incredible asshole. His callousness about other people and their suffering, and his wholesale support of the slaughter or suffering of other people if it would support him was disgusting. Also, he was so convicted of his own logic that he was unable to comprehend that someone might be smarter than him, think of something more correctly than him, or basic human psychology and the reality that it did not just apply to "others," that in fact many of his reasoning was based on his own inferiority complex and his insecure need to constantly reassert himself and that he was thus rejecting people with his hyper-aggressive feelingshiddentohimandsharedasfact. He thought whoever won the argument; that is, whoever was talking last, was somehow proven right. He also had a very Draco Malfoy-esk sneer, made me want to slap him in the face. And, whenever I got mad (say, at being repeatedly called The Socialist, because I did not support Ron Paul) that was automatically proof that he was right, and he would just singsong "I'm right I'm right" over and over until I shut up or physically attacked him.
I have nothing wrong with mature INTPs. They argue well, teach you how to play chess, and you incidentally find yourself wondering how open they are to being snogged.