It would depend on the thickness of the padding and the pencil thinness of the heel. But yes it would be possible, but permanent, unless it's very cheap carpet, I wouldn't think so. Unless the person is very heavy and stands in the same place for several hours, the likelyhood that it would leave a permanent mark, is nil to none. Even then, good carpeting is much more resilient then that. I've had hundreds of women walk on my carpets over the years with pencil thin heels on and I see no evidence of their traffic or telltale dents.