One of the most often mentioned "undesirable" characteristic of wood is its tendency to change color over time. "It turns yellow" is a common complaint when talking about lighter woods like maple. Darker woods are often criticized for "turning brown" or as is the case with some woods like walnut, "bleaching out."
The truth is, wood color does change with age. Freshly cut wood often exhibits bright colors and strong contrasts that, over time will become much more subtle. The exact nature of the change varies with the species of wood and the conditions under which it is kept. Padouk will be very reddish when first cut and after a while, the brightness will become more subdued and the wood will settle into a "reddish brown" tone. Maple will start out looking very light in color but over time it will take on a more "golden" or "amber" tone. Walnut may darken but if it is left in direct sunlight will lose much of its color.
The key in getting your customers to accept these changes is to help them to view them as an advantage. The interesting thing is that most valuable old furniture stores much of its value in the patina that the wood has acquired over time. Stripping an antique highboy may reveal glorious colors and grain patterns that were somewhat obscured by the "old finish" but doing so can completely destroy the piece's value. I try to talk to people in these terms, using the word "patina" often and substituting words like "golden tone" or "amber" instead of "yellow" which just sounds "yucky".
Instead of talking about a particular wood "turning brown" I talk about how it becomes "more subtle" as it "acquires character". I do point out to them that the one thing that affects wood tones more than anything else is UV light so keeping wood out of direct sunlight is a good way to slow the inevitable changes. But then there are woods like cherry that simply love sunlight and will become more and more beautiful the more they are allowed to bask in the sun.
To be continued ...