You hear about an addon from friends.
You hear about it from guildmates.
You read about it on forums.
You find an addon online that has 100 000+ hits.
You download the addon, log on to World of Warcraft, and test the addon.
You expect it to blow you away, and instead, it just plain blows.
What popular addon(s) have you downloaded that have just been disappointing.
For me, it would have to be Grid, IceHUD, and Archy.
Edit: Based off the first couple replies to this thread, you must now pick addons other than Gearscore. It's an obvious choice, there are already plenty of threads about it. I'm looking for people's opinions on popular addons that haven't been crushed beneath player's hate.