I use the little black nylon brush attachment for my seams. I turn the Dremel up on it's side, and use it more like a buffer with a very light touch.
Be careful not to dig into the seam, or then you'll have a trench where the seam was.
BTW... I sometimes use laquer thinner to "swell" up the seam before dremeling.
Here's a pic:
We clean latex seams every day.
I start by using a dremel tool with a bit that looks like a sphere with dozens of little tiny balls clustered all over the surface. It's actually intended for sanding rubber.
Then I smooth it by using 220 grit sandpaper wet with laquer thinner. A buffing with a paper towel wetted with laquer thinner finishes off the procedure.