Actually, I think I'm mostly annoyed by your use of three pejoratives to try to make one point, and the fact you spelled pseudo wrong just irritates some other part of my brain. :)
Sure, dandruff and 'dry skin flakes' are separate things entirely.
Dandruff is generally regarded to be caused by the fungus Malassezia. This fungus does not enjoy an acidic environment.
(Healthy) human skin tends towards pH 4-5 (there seems to be some debate). Malassezia likes 5-8 (again, some debate). Reducing the pH / increasing the acidity would appear to have some non-psuedo, non-alternative-medicine, non-falsehood foundation.
Wikipedia says one cause of dandruff is yeast-like fungus. Perhaps PH plays a role in that. Also vinegar has cleansing properties and may be less drying than detergent, and dry skin is another cause of dandruff.
The word "vinegar" is notably absent from that link. That solely shows that harsh soaps are harsh (which as you may have noticed is axiomatic), not that vinegar isn't.
When I typed the word "may" I meant it. If it's medically established that properly diluted vinegar dries the skin I'd be interested in knowing that. Otherwise, it seems like reasonable speculation to me rather than pseudo-scientific BS.
