Bad URL in ads

Found bad (404) errors in Adwords ads on my site. Is this normal?

[tigertom]

My Adsense earnings have gone down, so I thought I might use the competitive ad filter to remove ads for low quality sites, to see what happens.

I found about four bad URLs when hovering my mouse over some ads (I typed them in my browser to check them). Is that normal?

Reported a couple to Google, but gave up after the first two, as I don't want to harass them.

[Nitrous]

About 1 in 40 seems to be dead. 404. When people click does it still cost them? Or us...

[fredw]

It's my understanding the URL shown in the ad (or in your browser's status window when you hover over it) may have nothing to do with where the ad will actually go when someone clicks on it, so, you can't really test an ad by typing the url it displays manually into a broswer.

To really test an ad, you need to either:

a) Use the Adsense Preview Tool and click on the ad there or

b) VERY CAREFULLY (so as not to click on the ad) right-click on the underlined link portion of the ad and select "Properties" and in "Address" look for the url that follows "adurl=". That's the real url.

[Nitrous]

I always use the preview tool. They still dont work. I think the advertiser gets it wrong!