ime it depends on the needs of the music.
certain styles call for certain sounds...
rockabilly acts generally tend to like slap delay on their vocals, for example.
how useful effects like reverb can be vary greatly, depending on the acoustics of the environment....
you might be better off getting a dry, precise mix in a really cavernous room (like an old church).
worst thing i've dealt with lately are the tc vocal fx pedals...
dealt with 3 at a gig last night.
putting a cheap pre in front of a cheap pre in a regular bar beater mixer
is just a bad idea, and combined with poor bedroom settings on the users part can create some seriously bad sound quality and gain/ eq issues.
less is more, unless you are doing a dub mix -which is what i'm generally employed to do...
so i get to incorporate analog delays with feedback, looping, different verbs, kaoss pad etc. on vocals as well as the band...
trick is, just like has been stated before, it should be a part of the music and add to it, not distract from it.