Q:

Is a high thread count for bed sheets directly linked to how good the quality is?

Bed sheets often state the thread count as an indication of quality. Is the thread count really a good measure of quality? If not, what other things can be checked to determine the quality of the sheets?
Qualities people might be looking for in sheets are durability (& resistance to pilling), softness, resistance to fading, resistance to wrinkling. My experience is that most sheets are cotton, but I know some are a polyester/cotton blend, and there are other fabrics used such as silk. Obviously a thread count of silk is not comparable with cotton, but the same questions might apply when comparing silk with silk. 
Personally, I can't afford silk sheets, so I'm primarily interested in cotton or similar. 
Apparently the thread count is important enough to put in bold print with the item name:

A:

Choice is an Australian consumer watchdog and review magazine.
In a 2009 article titled Thread count is marketing spin, they warn that the published thread-counts may be misleading. 
(This is a slightly different argument to "Thread counts are unimportant.")
In particular, they highlight that there is no standard for how thread-counts are measured:

Since there is no legal requirement for manufacturers to state how they counted the threads, the term is almost meaningless.

They go one to warn that two-ply threads may effectively double the thread-count without necessarily being less coarse, and the coarseness of the threads may make similar thread-counts feel different.
Linen Place is a retailer (and therefore might have a conflict of interest) but in their explanation "The Truth about Thread Count", they explain the (US) FTC have made rulings about the definition of thread-count (and how the manufacturers have responded), so the situation may be different by country.

