What is science? It's considering as many of the variables as possible, forming a hypothesis, carefully testing with an open mind and accurately recording the results. Those who dismiss something they haven't even tried are not scientists, they are little closed-minded robots just spouting what they've been told. Science is discovery and discovery only happens when you are capable of saying "I don't know."
The correlation between blood types and different lifestyles is overwhelming in the anecdotal literature and the true scientists are working on compiling more information for further investigation.
The bottom line is very simple. Just try it with an open mind for a goodly amount of time -- a few months would be great, but most people notice changes in the first few weeks -- really follow the guidelines for your blood type -- at least 80%-90% -- keep a journal recording what you notice (again OPEN MIND!) and THEN form an opinion.
Unless you have the stuff to really conduct your own scientific experiment, in my book, your opinion has NO credence. If you've done a truly open-minded, whole-hearted experiment for yourself and it doesn't work for you, then your opinion has some merit and I'm willing to listen. But then I keep seeing over and over again the stories of those who did their experiment skeptically, even assuming it wouldn't help them, and then being amazed at how much it did help them.
I'm just starting my experiment and I'm complying between 95%-100%, which is very easy to do. So far I have pretty good energy, less allergic stuff and slightly better digestion, but I'm just one week into my experiment, and there are other factors that may be affecting the results. A longer trial will be necessary to get solid results. The jury is still out on the diet so I haven't formed an opinion one way or the other yet.
But, as you can undoubtedly tell, I sure do have an opinion about pseudo-scientists!!!