I'm nosey as hell (like all of you) and read the page to MOO... anyway, she mentioned the paint "bleeding" under the tape...anytime you paint stripes, shapes, etc. basically anything taped off that you want crisp lines for, paint over the edge of the paint with either A. primer, or B. the color of the wall. this "seals" the tape and you won't have the bleeding, your edges will be crisp and straight (as long as you tape straight ) HTH!!!
Re: paint tip (since moo mentioned it)