I sweat enough that it makes the faux leathers pretty gross. This is an bigger issue for my home chairs as I don't bother to put a shirt on before hopping on the internet.

In an office, while the chair at my desk probably stays there forever, there's no guarantee. Inadvertently swapping chairs happens all the time. The microbiological reality is probably the same, but my intuition is more comfortable with the idea that my successor might endure a mesh chair than a cushion sodden by my years of perspiration.