One of the things I heard the other day was that the rules they were operating under allowed for them to claim for things based in part on "common sense"/reasonable (or words to that effect), rather than hard and fast rules for what was allowed or not.
If that was the case then it's very different to if the rules were clear.
However some of the claims have stretched the definition of reasonable, or common sense to the point of breaking (reasonable is paying to have the garden maintained in a normal manner, it shouldn't include major changes/decorative features etc), and in many cases it looks very much like they've claimed for everything they possibly could, just because they could.
However it's the "flipping", and designation of second homes etc that I suspect is the bigger problem, and I look forward to some of them getting prosecuted for fraud (since when would anyone count their sisters spare bedroom as "main" accommodation when they have a family house where their partner/kids live, and they also spend a lot of time).
P,S,
I personally have zero problems with the geniune claims for reasonable expenses, it's the amount of fairly obvious mickey taking that winds me up - just because the rules don't specifically say something is wrong, doesn't (or shouldn't in people with any integrity) mean that everything else is fine.