I don't think that you will find a good definition of "reasonable wear & tear", on the internet or elsewhere. It is a little hard to define plus there are differences in local law and differences in how judges apply those laws.
1. Wear & Tear is different from cleaning. Some laws and some judges require you to return the apartment as clean as you got it, others say it has to be clean no matter how you received it. Sometimes, what is in the lease controls, sometimes not.
2. If something wears out (I mean WEARS out) it is generally wear and tear. For example, a light bulb burning out: the side of the carton of bulbs states it's average expected lifetime in hours, so it is expected to get used up just from usage. If you take out a bulb and drop it, thats not wear & tear, thats damage.
3. You asked about paint. Paint doesn't really WEAR out.
As I understand your situation, unit was painted before first tenant moved in, he stayed 2 years, then you moved in without painting, but we don't know how long you lived there.
Paint doesn't wear out. It gets dirty. Sometimes this is a matter of cleaning, which is your responsibility. Often, small claims courts make some determination of how long until the landlord should be expected to repaint, maybe 5 years or so, and then call that normal wear and tear. Less than that time, landlord can charge you, maybe on a pro-rated basis, longer than that is his responsibility. They usually try to put that under wear & tear laws, and it isn't really, but the court is trying to do the best they can to balance the responsibility.
If you move into a freshly-pained apartment, put your sofa or a table up against the wall, dirt will collect in the corner against the wall unless you are a very good housekeeper, and when you move out, there will be a black mark on the wall. It was actually your responsibility to keep clean, but as a practical matter, I always re-paint for a new tenant and charge only when there is some real damage.
4. Carpets is often a question of cleaning, and that is your responsibility. If the carpet is stained, then if it can be cleaned, that is not wear & tear but cleaning. If it can't be cleaned, it is damage, and then the question of who did the damage, you or the previous tenant, comes up. If it is stained, even if the previous tenant did that, and you lived there and walked on the carpet for a couple of years, you are responsible for cleaning, but maybe not for stains that wouldn't come out.
5. See the following about frequency of cleaning carpets:
https://forum.freeadvice.com/showthread.php?threadid=37483
snydekj didn't clean the carpet during 3 years that he lived there. That's gross.
toy has the carpets cleaned every two to three months. That may be a bit of an overkill.
Carpet experts recommend carpet cleaning every 6 months, and they recommend dry cleaning.
I think that AT LEAST once per year cleaning with hot-water extraction is necessary. My local judges agree with me.
This is by no means a complete discussion, only to give you some feeling for the kinds of issues that can be involved. I hope it helps.
[Edited by LL on 02-08-2001 at 03:26 PM]