'I liked their early stuff best' - A commonly heard phrase, usually written off as an attempt to look cool. However, it does make sense that the earlier works of a band, usually the stuff that got them famous, is often their best work. At this point, they are hungry, raw, striving to make it, and their sound is new and fresh - they are not limited by what they have already done. I'm not saying good bands always turn shit, but that it does happen. Here are the reasons why: (apologies for this being fairly electronica oriented, other examples would be welcomed.)

1) Creating an album that was so innovative and genre-defining, they have to force themselves to move on and in the process stifle the spark of genius that made them great. See Leftfield: Leftism; genius. Rythmn and stealth; occasionally genius, mostly overworked and rather dull. Also See Portishead: Portishead. Dummy was great, inventive, moving, funky and original. They then proceeded to ban themselves from sampling, in a desperate attempt to stay inventive, unfortunately extinguishing the spark of genius that made them great in the first place.

2) Trying to be clever when you already were. See Radiohead: So, OK Computer was a work of genius eh? well how often do you actually listen to it? And then, having critical praise lavished on them for that piece of self important crap, they finally vanished entirely up their own rectums like a 4 dimensional mobius strip with Kid A.

3) Equating DARK with GOOD: See Massive Attack: Mezzanine Their first two albums were marvellous with an air of emotinal intensity that acted strangely like a psychological inkblot test; you could superimpose your own mood on the music. Mezzanine offered no such option; dark, depressing and hard to listen through.

4) When you are no longer 14: see Rancid Offspring NOFX Green Day, and, no doubt for the next generation of naive young fools, Limp Bizkit, Papa Roach and Linkin park. also, Heavy Metal, Boybands, Happy Hardcore and many more . . .

5) Inventing and exhausting a genre all by yourself so you have to change the kind of music you make and thus becoming not very good.: See Fatboy Slim. He invented big beat with Better Living through Chemistry. Exhausted it with You've come a long way baby. Discovered that he wasn't that good at doing other things with Halfway between the gutter and the stars.

6) Not being that good in the first place, but coming up with a random moment of genius and spending the rest of your career trying to recreate it. See: ATB '9pm (Till I Come)' Admit it, it was good the first time you heard it. White Town 'Your woman' and thousands more.

7)Selling out. Limp Bizkit offspring green day and many, many more.

Disclaimer; i'm not saying that all the albums mentioned are unreservedly shit - most do have their merits - but that they did not do justice to the band that created them. Reading the list, mostly this comes down to Believing the hype about yourself and overthinking things.