Recently looking at the ads appearing on my page and wonder how I determine whether or not to filter them out if they are crappy advertisers
I determine the low payer by visiting the the destination of ads (using google adsense preview tool). If the site has an income from google adsense ads or another text ads (not an affiliate site or not selling their own product) then I assume that a low payer ad. But, there is some info I read it here at DP that said filtering ad is no good. Because google rank the ads by the most paid ads. Then the first ad that show (1st ad unit in html code) will contain the most paid ads. The ad perhaps not the one with higher CPC but has higher CTR so the combination will get you more adsense income. I myself had stop filtering ads months ago, and more focusing the time for building the site itself and leave the ads filtering to google.
There is a way that many webmasters do not know called AdsBlacklist http://www.adsblacklist.com/. Very useful for webmasters.
If you know your traffic (what they like and what kind of ad they would click), than you can filter ads (or websites) that don't match your visitors preference criteria