I'm not really in a position these day to use recycled packaging, except for bubble wrap, but used to use it frequently when I was selling off a large number of DVDs.

I would cut up old boxes and cut them to size so that I could send the DVDs boxed within satchels (they were wrapped in foam - a thin layer, usually recycled, then bubble-wrap, then cardboard casing).

I not only never had any complaints about this, but many comments about how well packaged the items were, so it's really about how well-protected the item is rather than whether the packaging has been used before.

The only thing that would really see buyers taking issue is food boxes that have stickyness, or grease spots etc. I have heard that some people don't like seeing recycled food boxes at all, no matter how clean, but if you were using anything like that, a quick note in the listing re: using recycled packaging to reduce costs etc should help.