If this is you, read on. Google AdWords has a feature called the "Site Exclusion" that allows you to select a certain campaign, then add any sites by URL to be excluded from that particular campaign. This is especially helpful if a site doesn't convert well, or if their users click ads to support the site, not to buy your product.
Another great use of the Site Exclusion tool is to exclude your own sites. For me, in one certain niche I have 10 websites that are all in very similar niches.
For example my sites are about widgets. I have a site about red widgets, blue widgets, new widgets, old widgets, etc.
For the site exclusion tool, I would add all of my sites to be excluded because I don't want my ads to be shown on my own sites. I have links to take care of sharing the visitors, I don't want to pay a middle man for the service.
If there is a site you don't want your ads to be shown on, just Exclude them!
