This is only a short post but very important for all those who value their guitars.
I have an acoustic guitar that I used for years, mainly to play around the house and for teaching. I wasn't doing any acoustic gigs at the time so I used to leave it out on a stand.
Sounds reasonable I guess...
After some time I started to notice some marks on the guitar and tried to clean them off but unfortunately found I couldn't. The marks were on the front of the guitar and I worked out it was the same spots the guitar stand kicked up to hold the instrument in place.
I thought this was interesting as I'd been told that these stands would not leave marks and were perfectly safe to leave your guitar on...this myth is still told around many music stores.
Eventually I decided to write the manufacturer and got this response... "Indeed no colored stand is safe to use with nitro lacquer finish due to the rest risk of the included colour." My stand is black by the way.
So the lesson is this; if you value your guitar, put it away in a case and don't leave it sitting on a stand for lengthy periods of time.
Chances are it could be ok, but I wouldn't take the risk.