Marks can definitely be a concern. I've been tied for the night numerous times and find that straps, cuffs etc that are not normally tight enough to leave marks suddenly do leave marks.

Usually I can hide wrists, neck, and (of course) ankle marks in the morning, but the week before last I ran into a bit of a situation. I was in a fairly loose hog-tie from about 12AM to 6AM--with a ballgag. This ball is on a fairly supple strap and quite comfortable. Unfortuntately, in the morning I had VERY distinct lines running up each cheek from my mouth.

It just happened to be a day that I absolutely couldn't take off work so I went and tried to avoid ppl as much as I could. One of my co-workers looked at me at around 3 in the afternoon and said (in a joke) that I looked like I had been wearing a "bit." I'm sure he was thinking of horses and had no idea that humans would do such a thing... otherwise he wouldn't have made the joke.

This has made my S.O. think a little more carefully when doing mid-week bondage, lol.