Not a lawyer, I'm guessing here. I'd assume the intention matters a lot. Scrape bots don't intend to cause trouble, they intend to get your data (for free). Same way as when some famous person tells people on Twitter to visit a website or when some poor blog gets the hug of death from HN. The intention wasn't to bring down the site.

Aside from that: is DDosing actually illegal (under US law)?