Dean had a weird feeling that someone was out to get him which didn't make him feel any better since he had discovered these kinds of feeling seemed to be accurate. In fact, many times Dean was able to understand what was going on even when he shouldn't have any clue. Mike just said that Dean knew how to read people and the room and understand things without being told. He held on to that belief until the night where he, Dean and several of their other friends played cards and Dean won every hand he didn't fold out of. After that, Mike just said he was physic.
Dean never put much thought into that though.
To many, Dean seemed like a rather perfect guy on the outside; smart, handsome, nice body, decent sense of humor. Only Mike really knew that Dean's biggest problems manifested at night.