In my experience, the 3rd tier search engines work best with “big brands” or at the least clients with a high-demand product. More times then not, I’ll test a Business.com or Ask.com and find A) I can’t generate any traffic or B) I can’t convert the traffic.

It all comes down to testing… But my one suggestion would be if your PPC campaign is built around branding, 3rd tier search engines can offer great (and cheap) exposure.

I’m catching up on my RSS feeds and came across your post … great information and suggestions that every pay per click manager should follow. I actually started doing this not too long ago and have found it to be a tremendous help. I am curious though .. you mentioned 3rd tier engines. Most bloggers/advertisers don’t even acknowledge using Ask or Business.com, etc. Do you have any insight so far as to when those work well (ie. verticles like real estate, auto, etc) or do you only use them for driving traffic for time-sensitive promotions, etc?