Very often when odds drop it means nothing
I don't agree. Of course it happens and even I can mention few examples, but definately not very often, like you said. philosophicalarf
gave the good explanation of this manipulation, altough if you monitor the odd till its closing (which I recommend) You can prevent from being "on the wrong side". How? Once you notice that odds trend is reversing and there's no value in your bet any more, you simply back off by playing best available opposite odd.
The whole system works and it's not questionable. You just need to put emotions aside and bet flat stake, no matter what , and in a long run You will always win. I bet over 500 matches based on dropping odds system so I know what I'm saying