It all went a bit downhill from this point really. Too much repetition.
I don't think it went downhill at this point, it peaked. 2007-2009 was when the show was at its most popular and funniest - if stagnant.
Apparently the show stopped featuring Freaky Eaters for its third series anyway when Harry found out it had been recommissioned purely because of its popularity on TV Burp. http://www.bbc.co.uk/programmes/p00ch4p4
- 1:08 in.
I've been looking for an excuse to mention this and as we're discussing when the show went downhill, I found this interview interesting, especially the point made about how the show's crew became divided between people who wanted more clips, and people who wanted more sketches.
Towards the end of the TV show’s run, the team had broken into two camps. One side wanted to focus less on clips while the other (the “TV Burp purists”) wanted to build it more and more around clips.
“I was always trying to make it into a sketch show,” he explains. “I was trying to edge out the clips whereas the others were trying to get more clips.”
It never descended into all-out war, but clearly something had to give. “I was starting to lose interest in it,” he admits. “I could always write a show. But I was starting to think we didn’t want to do a bad one. All the writers agreed.”
Worth a read if you're remotely interested in Harry Hill and/or TV Burp. http://www.bigissue.com/features/interviews/1920/harry-hill-i-was-bad-mood-six-months-year