I don’t like it when my AdWords ads are shown on parked domains, or on placeholder sites that pull in traffic through their domain name, especially porn-related ones.
For those who feel the same way, here’s a tip.
Go to “Campaign Summary”, then your campaign. Under the campaign’s name there are buttons for targeting settings, negative keywords and “Site and Category Exclusion”. On the “Sites” tab there, add the list of sites from this file (I’ll keep adding to it).
On top of that, you can look through the other tabs and, for example, under page types, exclude “Domain hosting sites”: parked pages with no content.