I didn't think the sample sizes were enough to be considered a meal. One would have to repeatedly hit up that sample stand to get enough to fill them up, no? And more than one helping or visit at the same stand is tacky (IMO of course)...you either liked it and will buy it...or you didn't like and will not buy it.
I would be mortified to treat the sample sarts like a free buffet. In fact, I'm not sure I've ever tried a sample from a grocery store. God only knows how it was cooked or how many people have coghed or sneezed over it while it sat there.
Note; I DO have cousins who do this. They also go to Buffet restaurants where you are supposed to pay for drinks and coffee at the beginning at the cashier, and then they get a table and ask the waitress to bring them coffee...this way they don't have to pay for it. They also found a couple of hotels near the hospital where their dad was last year, that served complimentary coffee to guests in the lobby and would go there for "free coffee" every morning before visiting him or work (sign above coffee said for guests only).