Many years ago I bought a birch tree mug from up north, and have been using it ever since. Now, some girls at work really object to it, they apparently think it's disgusting, unhealthy, gross, un-hygenic, and any combination of the above. OK, it does have a nicely built up patina like an old tobacco pipe on the inside, and when I put some olive oil on the wood for protection the coffe gets a slightly oily surface for a while, and the top edge gets a bit black, but come on! What do you say? Gross or not?