I thought Staind were really awesome when they did Dysfunction, since then, I'm not real impressed. GoRABmack obviously falls in here, and 311 is another band that was so great in the 90's, and now seem pretty uninteresting.
Dinosaur Jr. (I only really love their first two albums)
Red Hot Chili Peppers (I can't stand their new ****, it's dreadful)
Aquabats (they took away the trumpets, even though they always have sucked in general)
Tool (10k days, ehhh...knida boring)