Thanks for the explanation! I've talked with lawyers about this in the past week, and facts, totally rewritten summaries of fact, and collections of facts aren't copyrightable in the US, so it's not really an issue of their content, as far as I understand. They do have a right not to be crawled by me, though, especially if it causes a burden on them. I wrote that crawler specifically to be very light on their servers including making tradeoffs to usability (it never recrawls listings), but that's still their decision to make. If there are ways to get the data that don't involve touching their servers, then the TOU no longer applies, if I understand the law, but it would obviously make them angry, and so I'm most likely not going to do that.