Legality of YP & Other Scrapers?

Hi!

I'm just beginning to look into this whole thing. I thought I'd found a YP scraper that I was going to buy - until I read the guy's headline that said something to the effect, "Possibly Illegal Scraping Software Gets You Tons of Leads".

"Tons of Leads" sounds great. "Potentially Illegal" . .not so much so.

Does anyone have any real, good knowledge about the "legality" aspect of it? Or for that matter, any 'bad experiences' with it ... like the YP (or any other business) and their lawyers going after you? (What was the outcome?)

While I'm not inclined to tempt the fates and do something that is "potentially" illegal, just out of curiosity, how would they even know if anyone was scraping their information and emailing businesses with them?

Would they use a separate email address just for (tracking results from ) the YP?

Even if they did something like that, how could they prove I sued a scraper .. that I didn't just go to the YP myself and email the businesses listed there 'manually'?

BTW, can anyone recommend a good, affordable scraper - that scrapes the YP or any other source(s) - and provides a relatively high % of email addresses found?

I heard that software that scrapes the YP comes up with relatively few (25% or less) email addresses.

I've also heard that some software (more than just a 'scraper') is capable of giving information/feedback about Google Places, Mobile Sites, Bad Reviews. Can anyone recommend that kind of software?

Thanks for your time, in advance.

Richard