Digital Dissolve does not have many bad angles. The trick can be performed with people around you, forming a 270 degree angle, which means that it's not recommended that people are directly behind you.
The bad angles can easily be controlled, as people want to see the effect, and therefore should be in front of you, not behind. I'm sure that it's covered by Dan White in the DVD.
so far, i have had no bad angles...(noone behind me or underneath me) ...but ill try to do it for a crowd of people with some1 behind me, and see if i can hide it...ill let you know how it goes!
yeah so far underneath is the only bad angle i can think of!