mattg3 - 4:18 pm on Apr 30, 2007 (gmt 0) I don't think there is just one reason for 950.
It seems to me Google has two stages of penalisation. Level one -30 and -950 for the next level. _ONE_ of them seems to be tons of low quality similar incoming links. Everything Google doesn't like get's kicked to the end of the SERPS.
I don't think there is just one reason for 950.