Cavitation (http://en.wikipedia.org/wiki/Cavitation) is the formation of water vapour due to a very low-pressure area. It can happen routinely to a prop under heavy load if the prop is not properly cupped or pitched for the load to which it is subjected. The low pressure can damage the prop, although most commonly for small recreational boats, it will be limited to tearing some paint off of aluminum props. Low-quality or heavily-used props may acquire pits.

A completely different phenomenon is slippage due to air getting around the prop. This will typically happen in a tight turn when the water is choppy. The chop provides an opportunity for the hull, as it slides sideways, to close off a large air bubble between wave peaks. It is not a low-pressure phenomenon and does not pose the same risk of prop damage, although there could be small areas of low pressure as the water/air combination foams around the prop. Slippage is typically very short-lived. Since it involves an interaction of the water's surface and the hull, the hull design can play a part.

In real life, I notice no cavitation and only rare slippage in my Moomba XLV. The slippage only occurs when there is no ballast in use. Neither of these things are significant issues at all. Whoever is telling you about "boat quality" causing cavitation is experiencing a problem with "opinion quality".