Ads aren't facts. You're still intentionally copying the CL website without the right to do that. Good luck to you.
Edited: Not trying to start a "copyright isn't theft" debate.
There's a material difference - collecting data yourself versus copying someone else's collection of data.
As another example, can I go to Amazon.com (without using their API), scrape all the product names and prices off their web site and map the dates and times they change? I would think not. Those too are facts, but you're basically just copying someone else's database.
Can I scrape stock data off of Yahoo finance without having to pay the license fee associated with getting historical stock data?
Sure. There are plenty of services that do this, it's quite handy. Here's the one I use: http://camelcamelcamel.com/
> Can I scrape stock data off of Yahoo finance without having to pay the license fee associated with getting historical stock data?
Sure. They even provide a CSV format to make it easier for you!
Any service competing with Craigslist that uses those classifieds might not be stealing them, but its certainly in Craigslist's best interest to keep their most valuable asset safe.
I'm simply saying that Craigslist has a vested interest in keeping their data/facts/ads/whatever on their platform.