[woodruffw]

In my experience, it's uncommon to be called out for not leaving a tip, at least on the East Coast of the US. At worst, you might get a nasty look depending on the context (unlikely at a cafe, maybe at a nice restaurant with good service).

[Der_Einzige]

You run the risk of people spitting in your food if they recognize you when you return.

[wiml]

If they'll spit in your food for not leaving a tip, they'll probably spit in your food for other reasons as well. Best to simply avoid those places.

[woodruffw]

Why do you think that's even remotely common?