I didn’t undertake this as an experiment, but I have had exclusively “eelskin” wallets for about ten years now, stuffed with every kind of card in current usage, some in stacks and some right between eelskin partitions. No card of mine has ever shown any problem with its magnetization.
I don’t know what these “magnetic clasps” talked about could be, but they’re evidently not necessary for a perfectly functional wallet. I like these wallets because they’re vastly thinner than anything else I’ve seen, and in spite of the appearance that most of the thickness in the wallet is the cards, this makes a big difference.
I’ve never had an ATM card get demagnetized, but I’ve ruined several Metro cards, which are much thinner (paper) but still have magnetic strips. I finally discovered the problem was that I always kept my Metro card in the same little zipper pouch in my bag that was right next to the magnetic clasp. As far as the magnets go, I’ve never seen them on men’s wallets and only on very large women’s wallets- more like a clutch than a wallet. But I see them frequently on purses and small bags.
Hagfish are quite common in our area. They are disgusting not only due to their slime but also due tho the fact that they are blood sucking parasites. How this all relates to credit cards is unsure.