"Well your honor, we had a report of a tattoo'd man practicing law without a license. This man had tattoos on his face and neck and was holding a 6th Edition Black's Law Dictionary, so we stopped to talk to him."
Totally reasonable.
Again, it depends.
If you're saying police can't just walk up to a tat'd up dude and conduct a custodial interrogation, then you're right.
But, real situations are usually more complicated than, "I stopped him because he has tats."
The original comment that started this line was that someone had stated that LEOs should be able to stop and frisk anyone that looked like the suspects in the robbery/homicide at the mall. That was the entire premise behind my comments. Specifically, that a LEO cannot simply stop and frisk a citizen because he has visible tattoos or even because he has specific tattoos (prison/gang).