Flashflood is the most frequent violator of this fallacy. In a way it's really a moot point. At the end of the day, it does not matter how doubt is reached. They still cannot support their position. Their only recourse is ad hominem, which is what this is.
I am skeptical, not cynical, and I will change my position on the presentation of robust data. I have in the past over many things. However, no one has presented any robust data where AltMed is concerned. All thats been presented in a long line of fallacious arguments and personal anecdotes. The exact opposite of data. They can't claim we are closed minded or cynical simply because we won't accept poor data or the fact their claim is scientifically implausible in the first place.
Their next fallacy when they get nowhere with this one is reductio ad Hitlerum (e.g., "they are Nazi-Skeptics" ). And yes, Flashflood again....sigh.
"It's good to stay open minded but not so open that your brain falls out"