What is a common challenge or problem with backgrounds?

Distracting backgrounds, moose antlers etc

Explanation:

When taking photos having a very colorful background can be very distracting. It takes ones eye off of the vocal point.  Another common problem is a term called "moose antlers".  It's when something from the background looks like it's part of your head or hair etc. Like a branch in the background may look like bunny ears etc.

Having clear, non distracting, backgrounds is the way to go :)

Hope this helped.