Here's a perfect example of something that rubs me the wrong way.
While installing AVG free edition, I'm presented with this little dialog:

Notice the options I was given, and how they are nested. First of all, I don't like opt-out installations. These boxes should be unchecked by default. Second, logic (and long experience with GUI's) would dictate that if you uncheck the top one, the bottom one will also be disabled. Not so:

So if you're not paying attention, Yahoo! becomes your default search engine, and you open yourself up for more spam.
Now, don't get me wrong. I love AVG, it's worked wonders keeping my system free from malware. Someday I may actually upgrade to the paid version just to show my gratitude. But rule No. 1 for me is "All installations must be opt-in and not opt-out." Checking crap on my behalf that I may not want, and might miss if I'm in a hurry, is underhanded and deceptive. AVG's a good enough product that they shouldn't stoop to this particular tactic.
*yarg snarl snap yarg* 