"Well, it's certainly uncontaminated by customers."

Dear used bookstore proprietor person:

Yes, you did remember me correctly as the same person who had sat down with a handful of books for roughly half an hour, and then left without buying any the other day. Yes, I was about to sit down with a handful of books again when you told me that unless I were going to buy something, browsing was not okay.

Speaking as someone who owns roughly a metric fuckton of books, I feel obliged to point out (again: yes, I did say something to this effect and I realize you were resolutely unmoved): generally speaking, most bookstores cheerfully allow for, even encourage unlimited browsing. This is not because they are kind generous people; this is because they understand that in bookstores, generally speaking, the people who sit there and browse are repeat customers; and yes, most of them do buy something, if not this time, then next time, or the one after that. For example, today I went and browsed in a different used bookstore, and they left me the hell alone, as they always do, and I ended up buying two books. See how this works?

Well, no, I can see that you don't. Okay. What I didn't say: you may also want to consider that maybe the reason you remembered me was because I was, that time, like this time, pretty much the only person in the store.

I mean, I'm not suggesting your attitude is the only reason for business being slow: the economy's bad, used bookstores aren't necessarily always exactly booming, and also your selection is kind of crap. But yeah, there was one book of food lit/crit I'd never seen elsewhere and I was seriously thinking about buying it. Even with the plastic on the cover and the relatively high price. Still, I'm sure it was worth it not to have to deal with the annoyance of watching someone look at books, in a bookstore, that you run.

You know what would really solve the problem? If you just got rid of all the books. You could have, like, those dummy copies they have in furniture stores, you know? It'd be great. And the customer could come in and be like, "Do you have anything in red?" and you could lead them silently to the back and glower at them until they found the right one to match their drapes, and paid for it.

Addendum: if you were even half this entertaining in your churlishness, I would have gladly let it pass. Sadly, you are not.