I wouldn't like it either; not only the invasion of privacy thing but like Lois I like my washing to be sorted - into colours and fabrics - so I wouldn't like a day's clothes just lumped in together. I also do knickers etc on a hotter wash than some things...
I know people I've lent things to who have turned the white stuff grey because they don't sort things. Needless to say, I won't be lending them stuff again. I can't stand it when people put the whole day's wash on, no matter what colour it is - you can always tell as their whites are mucky coloured.
Sorting the wash means you do have piles of washing but it's more eco friendly to do a full wash anyway, right?