I deliberately use recycled tapes for most of my self released stuff.
I've dubbed hundred of tapes on tapes made for teaching the Bible to kids for instance. It was even cooler when I used some of that batch of tapes for my older black metal band.
I do it for aesthetics, plain ethics, sound, and also because I had enough experiences of duplication plants messing with the mixes, cutting the beginning of a song on one side, etc... Also, I believe that the few people who ask for my stuff may enjoy knowing it was all made at home for them. It takes a considerable amount of time but I also personally really dislike when buying something from the underground feels the same as ordering whatever random commodity I need from Amazon. But I guess I'm just a nostalgic fuck who still daydreams of when he was ordering records through phone calls and wasn't surprised when a package came with a handwritten note. Whenever I get a tape with a plain-colored shell and 1/2 or A and B scratched on it by what seems to be a handicapped 7-year-old, it drives me nuts. However, if I do get a recycled tape with some extra material left on the dubbed side or the B side, I begin wondering about it, and it greatly enhances my experience of the release or "relation" with the artist.