“And yekke2, old question. Pashtus PAA is right, although it’s not so ????, especially as all the Elves are doing is picking them up. So Dobby in his time at the Malfoys could have just picked up some clothes. And can all House-Elves not work with clothes? ???? its ???? on ??? ?????.”
In Dobby’s case, Lucius literally gave him a sock. House-elves are freed when the masters physically present them with clothing, not when they have to work with clothing as part of their job– so laundry wouldn’t count.
However, Hermione does not physically give her hats to the house-elves in Gryffindor Tower. The hats nevertheless have the power to free the elves because she planted them with the kavannah that they are gifts. (So if she just carelessly left her own hat lying around, a house-elf could pick it up and return it to its place without being freed.)
Hmmm. Are there two separate ways of freeing? It seems very strange to say that either by mistakenly giving or by intentionally leaving clothes one can free an elf. Surely either a maisah nesinah or a kavono leshachrer should be good, but not both!