While I am somewhat dissapointed by D'Adamo's lack of footnotes, and frustrated by his avoidance of indexes, I haven't yet found a credible direct dispute to any significant claims of his. I am aware of a text that might indicate behavior of lectins on stomach tissuus would need to be directly studied, but I wasn't willing to spend in excess of $200 US (iirc) to find out what exactly it found, depite it being a "real" scientificly strict (apparently, as I didn't actually get to read the) study. 
While not as rigourously strict with the science as it should be (at least what is presented in his books) ER4YT doesn't seem to be significantly paranormal or disprovable. So while it has a stigma of pseudoscience, that stigma hasn't really been justified.  Some supposed refutation I have come across turned out to be of even poorer quality, either reflecting it's own pseudoscience, or a lack of familiarity with the nominal subject. I would really like to see some explicit, maybe even rigorous debunking of D'Adamo's (occasionaly controversial? I can't see why) offerings. As of yet, I consider this closer to protoscience than unfalsifiable pseudoscience. 
In any case, I don't think that anything I previously posted on this matter is all that fantastic.  Is the mere mention of Doctor D'Adamo, or Eat Right For Your Type (ER4YT) enough to invalidate the respose I offered?  Other than that vague stigma, is my above answer to the utility of divergent blood types unhelpful or incorrect? I do believe that I was careful enough to avoid anything that wasn't NPOV.  Maybe, I shouldn't have tread so lightly, so as to provoke more of a direct response.  Because while I like how it advocates my [Type O] consumption of most animal proteins, I find it's avoid lists including wheat and dairy to be cumbersome.