I for one don't like slam poetry, there's something that distinguishes it from other forms of poetry that I just don't really like. It feels too much like rap music to me. I don't know... there's something about the way the emotions are expressed - I think perhaps because they are so confrontational, and occasional they are attempting to sound subtle (which I have never heard one succeed at).
One thing to add: I don't really like rap music, but what you will find is that slightly (but not really) ironically I respect true thugs (hear me out). I define a true thug as someone who is going through some things that they may not like, but accept that they have to deal with them, and aren't obnoxious about it. I see slam poetry as that obnoxiousness. Now, another facet to take into account is that I like Rage Against the Machine. The reason I like them is probably because I only have one song to judge them by, so in my extremely limited experience it's their one musical climax of rage. I can be a pretty emotional person when I'm not utterly calm, so when I hear them screaming as loud as they possibly can I think of a crazed person enraged at the atrocities that they percieve to be attacking something they are closely attached to. Compare this to... uh... if you're into rap fill me in here, but like someone who's essentially whining (Actual whining I despise) about something. This is how I see slam poetry - a way to gently dominate someone. I don't like that. If your point is actually that important, you're gonna be insane with rage.
I could very well be wrong about anything I just wrote, but I see slam poetry as a weak, fake expression, and I don't like it. You might I think the same of poetry; in fact, I don't. I have seen two types of poetry I like. One of which is a delicate way of entertaining the reader, and the other is "Sometimes You Just Get So Alone It All Makes Sense", a book of beat poetry that I thought was interesting, which is about as close as slam poetry. But there's still something different, I spent this whole post trying to figure it out, and I didn't.