The devil's carpet?

My knees are starting to look like bacon thanks to this stuff, we played on a pitch last night that wasn't too bad, I think it was made of recycled tyres or something.
The worst is the old skool sandy stuff, fall over and you're picking sand out of a raw wound for days...nice. There's one pitch in guildford that's a beach, everytime you kick a highish ball sand goes flying everywhere, and when it rains it almost turns to mud.

What's the worst surface you've played on?