I know, I just saw the disposable cups, too!! I was thinking, how lazy can you be you can't wash out a cup? Anyway, I never noticed an oily residue, but it just freaks me out even more thinking about it. Ds has some different cups, and I've noticed that the ones that you can see through are much worse than the ones you can't see through. I've started letting him use sports bottles when we're out tho, since I've never noticed a smell/taste from those. I wonder why some plastics are really bad and some are not. Then I wonder about the plastic I use with food in it, I wouldn't be as likely to notice a smell or taste.
I went to wal mart the other day because I know they sell enamel plates and stuff in the camping section. They had big coffee mugs, but not ones small enough to be suitable for kids. I thought I remembered seeing ones that were really small like for that special coffee that some people drink. What's that stuff called, esspresso? Is that right? Anyway, I also did a search, but couldn't find anything online.
You know rereading himalayan girls post, I'm wondering if paper cups with lids and straws might be a good alternative, I know not good for the enviornment, but do you think that's safer, and better for littler kids to handle without spilling?