You'd probably be okay so long as you treat your potential customers respectfully whether they buy or not

I went to one seminar (admittedly to get the free plane tix only) and when the guy realized I wasn't going to buy, he threw his pen across the table. I had told him right up front I wasn't going to buy so that he wouldn't waste any real time on me, but he kept pitching and finally pitched a fit. Oops :/