Ryn If you are talking about teams occupying league positions (which is of course the best indicator of a season's form), there are results up and down the leagues every week which don't work out as they 'should' do.
Arsenal Vs West Brom and Norwich Vs Hull come straight to mind from last weekend. If I looked for some results on teh internets I'm sure I could find more examples where 'form' teams have been beaten at home by bottom six sides.
As a betting man, I'd agree. I've given up serious betting on football because I've never found a system that would more than break even. (Rugby handicaps are much easier, in my opinion; horseracing, a write off.) The obvious thing to do would be to back teams that had won their last few at home, if they are playing at home against teams that have lost their last few away. And because the odds would be tight, put them in a treble. But it's virtually impossible to get three home wins using that method, I found.