I do agree with what everyone is saying here. I believe and may not be correct that a dj is someone that knows how to play the right music to the corect crowd. This can be difficult as i have found out by my own experiance. He/She must love what they play and not do it just to please someone who is paying them (also known as Bollotics). Not affraid to introduce new music and try to mix different styles together, this could be salsa with dancehall or rap with drum and bass (how about Mozart with Biggie? Maybe not). If they are enjoying it then the crowd should to. I don't think it is very important to be able to beat match and or any of the dj gymnastics some tend to do which can become boring if not done right.
I can't scratch ( I wish I could) or any of the fancy stuff but I do know how to beat match. Some of the best parties I have played at have been with one turntable. I have moved away from parties and clubs and now stick to studio work and radio due to other responsibilities. My moto what i have always stuck with is 'if it sounds hot play it'. Still have the pasion to source the newest and rare music of many genres.