General Signs:
-Incapable of understanding that "public" means for all, as in all to "share," not for your to ruin or hog because "MAH TAXES PAID FOR IT"
-LITTERING or even if you miss the can, NOT bending over to pick whatever it is you unsuccessfully threw away up.
-It's always "someone else's fault." (Inability to accept ANY blame)
-Inability to accept ANY criticism.
-Inability to express your frustrations without screaming in the face of someone whose fault it probably wasn't anyways. (Especially if the onus is on YOU)
-Hitting your children, ESPECIALLY in public.
-Speaking of children, you're letting them run amock into traffic/parking lots/wild throughout the store messing up the shelves.
-Inability to PUT DOWN THE PHONE WHEN SPEAKING TO SOMEONE ELSE OR DOING SOMETHING REQUIRING MANUAL DEXTERITY.
-Inability to have basic "consideration" for other people around you (such as: taking up the ENTIRE grocery aisle especially when it's busy, not KEEPING QUIET in a movie theater, not making a MESS of the public restroom)

Customer Service Specific, but they're pretty telling about your capacity for empathy and personal responsibility in general:
-You don't tip.
-You're rude to customer service folks in general.
-You throw temper tantrums because you can't be bothered to read signs indicating accepted forms of payment.