...we were under constant pressure to do far more awful and dangerous things in the name of ’stickiness’, and we refused.
The accepted goals of our team were simple:  once we’re installed, stay installed until the user asks us off  make sure it’s the user asking us off, and not a competitor’s code  when the user asks us to leave, leave. We took all three points very seriously.
That second requirement was why you had to download an uninstaller (which used a captcha): anything already on the user’s machine could be reverse-engineered.
When users did have trouble getting us to uninstall, we were actually horrified, because once you misuse the magic there’s no telling how bad things might get.
As for unauthorized installs: we didn’t just wait for user complaints, we actually ran multiple webcrawlers designed to detect drive-by downloads.
Even so, it was a dance with the Devil. As with much ordinary advertising, we were exploiting people’s naivite and/or stupidity; I’m glad to have it behind me.
I've added Superantispyware to my computer as a result of a comment there, and it's found some malware already. (I don't add programs without googling for reviews first.)
Page down to paperghost's comments for a considerably less sunny view of Direct Revenue.
Link thanks to Existence Is Wonderful, a blog I recommend.