After Reading Topics And Posts About TPG's I Leave The Forum Depressed?

I often see TPG straight-graded LWC and Indian cents that have very vivid toning - electric blues and magenta colors are fairly common. I don't know what goes into the TPG companies' determination whether a coin has been artificially toned; I'm sure others more knowledgable than I will chime in.

Just a suggestion on storage of coins in an environment as you describe. I bought an inexpensive dehumidifier I use in the small safe room where I store my coins (I just have to empty the tank once a week or so), and I store everything in Intercept Shield boxes which reduces air circulation and provide protection if there are contaminants in the air. I've not noticed any change in toning of any of my silver or copper coins, TPG holdered or raw, in the 15 years or so I've been doing this.

I am not buying high value coins or what I consider to be high value. There are so many coins of questionable color. I wish I could find a book of most types of altered Lincolns and what's the obvious clue I am missing. What constitutes a weak strike and pictures to go with it. Is it possible PCGS and NGC would prefer you to send in coins instead of recognizing less obvious altered coins on your own. I often hear that it takes looking at thousands of coins before you get the feel of what they should look like. I call B.S pictures would shorten the learning curve in my opinion. WHAT SAY YOU?

I really do think experience is going to be the best teacher ultimately. It takes awhile to look through thousands of coins but that's honestly what I did in building out my Lincoln collection.

There's always the dreaded concern of having a TPG problem coin but I try not to get too hung up on it as I mostly have raw coins in my collection and focus more on eye appeal than ultimately what someone else thinks of it. I do try to understand what it is I am buying and have learned the following about the various problems you identified:

cleaned - first and foremost with higher end copper is luster; cleaning usually kills luster so I like to see some luster on higher grade Lincolns. I also am skeptical of uniformity of toning - not that it doesn't happen but some variability is to be expected and says "this is natural"
artificially toned - kind of to the above, any type of wild blue or purple uniform toning is a point of suspicion for me. Again, it's possible but in my experience not how most copper coins tend to tone
questionable color - this is a tricky one but the typically progression of copper (Lincolns is what I am most familiar with) is from bright red to deep red to red with brown overtones to mostly brown with a hit of red to brown. I can't really describe questionable color but it tends to stick out when you look at a group of coins
some type of problem - some of the other problems can be a mystery. My 1913-S Lincoln was cracked out of a PCGS slabbed marked "Smoothed". I am not sure what that even means but I was happy to take the coin at a big discount and put it into my Dansco. It is a nice looking coin. I'd go back to eye appeal on some of these ultimately.

I think for most collectors with a modest to moderate budget, sometimes compromises might have to be made to complete a collection. Coins with small imperfections but good eye appeal can have a place in a collection when you are on a budget. I know some would disagree and say save up until you can afford problem free for everything but I go more for mostly problem free

Glad to help, welcome to the forum!