3. The embellishments look totally stuck-on.
It's a bad sign if it looks like you could repair your dress with a hot glue gun.
The smaller the individual embellishments, the better. That way, they will look like they are actually part of the fabric, and not like they were just slapped on at the end. It's also a good idea to stick with more abstract embellishments, which are less likely to distract from the overall look.