Well said P57 and Partypooper... Although I just skimmed your posts, I think they contain my thoughts exactly.

PrePost odds in the newspaper are just how 1 person has rated the fields...
The Late Mail, is just somebodies tips.

Information is power in this game, and if you rely purely on one source for punting then you might as well just cut a hole in the bottom of your wallet now.
And yes, if this one person that you are relying on their ratings, is only good at rating on certain days then please find another hobby.

There is another thread about suicide and the martingale system at the moment. I would suggest that this would be step 2.....