Actually, dirty laser lenses are one of the most common problems with older players. A lot of folks just ditch their players when they get old and start to skip, because repair costs can be so high, and parts for older players are sometimes hard to find. But sometimes all you need to do is just dust things off...
I used to live in Martinsburg WV. I lived in a house that was built in 1911, and had the original casement windows, and was VERY drafty.. Martinsburg had, within 2 miles of my house, 3 concrete fabricators, a brick manufacturer, and one of the largest printers in the mid-Atlantic region (Quebecor World). Needless to say, there was a TON of particulate pollution in the air there. Luckily, there aren't many cars because it's mostly rural, and there is no heavy industry and the closest power plant was something like 10 miles away, and Martinsburg sits on top of the ridge of the Appalachian mountains in that part of the state, so there wasn't any smog.But my house was so dusty that you could write your name in the dust on a coffee table 2 hours after you dusted, if it was a breezy dry day and you had the windows open. In the winter, I heated with a 20-year-old oil furnace, which brought it's own special brand of dust--a nasty dark gray sort of stuff that sticks to EVERYTHING. Man was I glad to move out of THAT place....
After having an older Sony CD player, my Meridian 208, AND a Sony DVD player ALL start skipping and mistracking about 6 months after I moved there, I used lens cleaners on my CD players and my DVD player about every 3 months, and they never skipped again the whole time I lived there.
Most people on this forum will probably a) never live in a location (or a house) that will be that dusty, and 2) never live in a house that doesn't have central air, so you're right, lens cleaners probably are something that most folks on this forum will never need. But if you have an older unit, and it starts to skip, the FIRST thing I'd do is get a good-quality lens cleaning disc and give it a shot. The next escalation in the trouble-shooting schedule for skipping CD players is to manually clean the lens, which involves opening the case and getting at the lens with a VERY soft-headed Q-tip, which is not something for the faint-of-heart. And if you're going to do that, you might as well clean and re-lube the gears and tray assembly too, which is probably something most folks (except the most die-hard tinkerers) should leave to a professional technician...
Many people don't realize just how much damage accumulated dust can do to their gear, especially components with moving parts like CD players, or gear that generates heat like amplifiers. If your amps are on the floor, you should probably open them up every year or so and blow all the dust out of the chassis with a can of pressurized air (like for cleaning computer keyboards). You would be AMAZED at the size of the dust bunnies that can accumulate on internal heat sinks, and banks of transistors. To an output transistor, a good layer of dust is like wearing a ski parka in a sauna.
Clean gear is happy gear, that's for sure.