[wrath]

I've built several businesses that either relied in-part to scrapping/indexing websites or solely relied on scrapping/index websites. I We never achieved the success of Google but we did get large enough to be noticed by some sites (Amazon for example). We did face legal issues but of a different kind. There were a few bugs early on that made us hit websites too much and we did receive a couple of cease and desist letters. We fixed our problem and explained the situation to the site owner and everything was resolved.

The only "fair use" type issue that we encountered was using logos from websites. E.g. Displaying the logos of the websites we indexes on our site. Once again, nothing serious came of it. I believe our marketing department removed the logos and put text instead.

Personally, I wouldn't worry about these issues until it becomes a problem. When it becomes a problem it means you're on to something and you're disruptive enough to get some attention. It's a good problem to have IMO.