Umpires relying on guesswork?

From Alan Rhys-Thompson, United Kingdom
I am interested in the way umpires seeme to apply different standards of "being certain" (the sole criterion for giving a batsman out as I understand it) as between lbws and 'bat-pad' claims. For the former, they appear to me to be if anything over-scrupulous (especially hard on spinners, as has been noted!), not that I have any problem with any last sliver of doubt going the batsman's way. But that's just the point.

It seems to me to be far harder to be "certain" when it comes to 'bat-pad' decisions, but they seem almost to be given on guesswork. Paul Collingwood's dismissal at Headingley was a classic case. How COULD the umpire be certain in that case, as the bat was a fair way from the ball? I bet he just THOUGHT it hit the bat! I have used the word "seems" a lot, because I don't want to appear dogmatic about this, and just wonder if other viewers share this opinion.

Of course, as England batsmen seem incapable of playing any spinner with a sliver of talent (and God help them when they meet up with this new star, Mendis!) so are frequently out prodding forward, leaving themselves open to the umpire's whim. Am I being unfair to the men in white?