When I first started knitting I thought "knit dishcloths?!? are these people crazy???" - but then I knit one up to try the knit/purl image thing and, since it was done, started using it. At first I thought, eh - not so great. Then I washed it a couple of times...and now, it is ALL I use in the kitchen and I have a list of requests by family members to make them some. As they are washed they become more absorbent and they just pick up the crumbs on the counter so well, and scrub so well, and...well, you get the picture.
So, simply put, yes I use them - and they are great for trying new techniques and patterns 'cause if you make a mistake, well they ARE just dischcloths!