In Japan, many "deli-style" places that sell food have a little section in front with samples for you to try. Japanese people haven't the slightest qualm about munching down on one or two samples and moving on to the next booth without a thought. Apparently, people on vacation have been known to actually fill themselves this way in lieu of meals (*cough* you know who you are).
Maybe this is a personal thing, but I can't take and eat a sample without feeling at least some semblance of guilt for not taking interest in the store in question. Perhaps it's a waste of my time and energy, but I feel some sort of obligation to show an interest in the store's wares. I see all the time people walk to a booth/store, take the sample, and walk straight away without a backward glance.
Is this just me, or am I carrying with me some sort of cultural guilt?