I imagine "no guns" signs are intended to attract anti's as much as they're intended to fend anyone off. It's a socially acceptable political sign.
In all honesty I don't think I've ever seen one. If they started popping up I'm not sure what my reaction would be. Some places I'd avoid, some places - the ones with really good food/prices - I'd probably keep going to. Most, what with wrangling kids, I'd probably not notice.
si vis pacem para bellum