politicalamity06

There is nothing wrong with your guitar. It's not the humidity, or the case (lol, that's a new one), or the truss rod, or the tuners. You are not installing your strings correctly. If your luthier did not explain this to you, I would question his experience no doubt. The problem is a combination of things. Once you understand these and compensate for them, your guitar will stay in tune. First as stated, you must lube the nut(pencil shavings work fine for this). Second, you must lock the string around the post (you tube will show you how). Third, use as little wraps around the tuning post as possible. Fourth, Ernie Ball makes strings that are reinforced at the ball end to prevent the wrap slippage at the stop bar. These are the best strings i have ever used, and assist in helping the guitar achieve rock solid tuning stability. Finally, adjust your intonation AFTER you have stretched your strings. As any string stretches, the intonation changes. You need to make sure your strings are fully stretched or your intonation will be off and you wont play in tune. My les Paul rarely drops out of tune. As a matter of fact, it stays in tune better than my Floyd rose Guitars. I have ZERO tuning issues because I have followed the steps above. Hope you read this, because I know it will help you.

You don't need a new nut. Make sure you are "locking the string" around the tuning post when you change strings. You tube has many videos of this if you need assistance. This is the single most important thing i did to improve tuning stability. Second, ensure your strings are properly stretched. Third, after your strings have stretched, adjust the intonation. The intonation of strings changes as they stretch.. You will only need to do this step once and also if you change brands or gauges of strings. It will also help if you install better tuners than the standard plastic tulip style on most Les Pauls. Locking tuners are the best but standard Grovers are excellent as well. I put Grover's on mine and it helped a bunch. I also switched to earnie ball RPS strings. They are reinforced at the ball end and help to insure that the wrapped end does not slip any after the initial stretching period. I do not have tuning problems any more and you won't either if you follow those steps.