It depends on how you imterpret "trick". Some say 'trick', and they mean "egg somebody's house and key their car!" Now that's mean. Other people will mean it like "hide behind a bush and scare kids as they walk by." Lots of fun, and no real harm done in the end. Usually.
If you celebrate Halloween by dressing up in a silly costume and going door to door asking for candy, I think it's perfectly fine.