I have personally used the blog MOD, and I hate it. It was being spammed so bad my site got suspended, and it's coded so poorly it's horrible. Another thing to note it that it doesn't work on PHP5 without extra tweaking.
Shoutbox spam? Yeah, I had to adjust it so only registered users could post messages. And I've got a lot of the SQL queries cached. But otherwise, I haven't had any problems. Maybe I've just been lucky so far...
But I know what you mean about getting bad mods with no review. I've come across a few bad eggs myself, mods that look great, but make you barf when you look at the source.. *cough* ShopHack *cough*