Here’s some posts I’ve made in the past about why I stopped using TLA:

1. Goodbye Text Link Ads
2. More TLA trouble
3. TLA - beginning of the end

In summary, I don’t think it’s an ethical advertising model, although that issue is debatable and depends on one’s point of view. Secondarily, though, whether it’s ethical or not, Google is now actively penalizing sites that use this type of advertising, so that’s reason enough not to use it, if nothing else.

The terminology is a bit confusing, because there are also legitimate “text link” ads, which contain the “nofollow” attribute and therefore are not designed to sell PageRank. Google itself sells ads this way, and I have no problem with those.