> [Government] which is now holding websites liable for any illegal advertisements shown on their pages.

This could turn out to be a very dangerous precedent to make, and not good news at all for any listing related startup.

Even if you don't want to host these illegal ads, and you put measures in place to block and remove them, you might still be held liable. I'd hope they go after the main violators (both of the law and Adwords ToS) and not their unwilling messengers.