UPDATE:

So, I have been wearing these slippers almost daily for the last four months, without socks.  The slippers are still comfortable, but the arch support has collapsed a bit, which I imagine is normal.  Also, unfortunately, the slippers are becoming too smelly to wear!  I don't know if this is because I've been wearing them without socks, or because they are closed slippers (not slip-ons), or some other reason.  But it is troublesome, and I am considering some open slippers.

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Ok.  I spent a RIDICULOUS amount of time researching sheepskin slippers.  Ridiculous.  I knew I wanted moccasin-style real sheepskin slippers, preferably with some arch support, and with a sole that wasn't just a hard layer of rubber.  After returning one pair of Smart Dogs, and nearly purchasing a pair of the really expensive ones, I got these today.  And... I love them!  They are exactly the old-man ugly slippers I was looking for.

One consideration:  Several of the reviewers commented on the sizing, that they run rather large.  I think this is true-- I am a pretty regular size 8, I ordered the size 8, and they were big right out of the box, slipping off the heel.  So, if you have a bit of patience and are willing to take the time to stretch them out, then ordering a size down is probably the way to go.  Or, as I did, you can tie the laces tighter to accommodate for the larger sizing.  It's really just a matter of preference.