The answer you found on Yahoo is mostly wrong. The basic statement (same as dpollitt's answer heredpollitt's answer here) is correct — theoretically, image quality shouldn't degrade but a number of factors might make it worse. And the list of things that might go wrong is sound enough. But the mapping of symptoms to problems is very inaccurate.
This can definitely lead to distinctive dust spotsdistinctive dust spots. However, for there to be overall resolution loss, there'd have to be an even coating of dust, which seems unlikely. False colors and noise are unrelated.
This is just wrong. Stuck ("false-color") pixels are common, and can increase as a camera ages, but they're not generally due to improper maintenance — unless you're taking long-exposure pictures of the suntaking long-exposure pictures of the sun, and that case the damage is likely to be distinctive. "Resolution loss" isn't an issue here: if you have a 10 megapixel camera with an insanely-high 1000 dead pixels, that's only 0.01% of the resolution!
This is more likely to lead to the lens getting jammed than to the problems described. In general, dust in the lens is undetectabledust in the lens is undetectable, although if it's on the rear element you might see some light shadowing under certain conditions. If it's a huge amount of dust, you'll have a small loss of resolution and contrast. (Not "noisy, blurry and distorted images".)
A missing lens coating would make your lens more susceptible to flareflare and to veiling glare, which could reduce overall contrast. A partially-damaged lens coating would probably be a visible scratch, and that basically falls under the same category as dust in the lens.