An unpleasant noise is not necessarily abnormal, and even an abnormal noise (in the sense that most of the vehicles don't emit it) isn't necessarily a sign of anything actually wrong (in the sense of causing damage or shortening the vehicle's service life).
Story I heard from a Harley tech many years ago: the Evolution motor was designed in the days of high-priced, low-octane gas, and so was intended to run on regular (87 octane). The simple two-curve vacuum advance system (low vacuum triggers a switch to a less-advanced rpm-vs-advance curve) had the quirk that it would generate a fraction of a second's worth of spark rattle if you rolled the throttle on in a wimpy manner. The factory said this was harmless, and the three Evos I owned that all went well over 100,000 miles.
The tech told me people kept bringing their bikes in and complaining about "engine knock." After a road test, they'd be told this is normal, it's not going to damage anything. This didn't go down well--"I didn't spend all this money for a bike that makes funny noises!" So the factory said, fine, you don't want to hear this perfectly normal sound, then fill it up with premium (91 octane) gas. This made customers happy. Eventually, the company started listing premium as the required gas for the late Evos and Twin Cams--not because the engine needed it (an engine with 8.5:1 compression does not need 91 octane fuel), but because that was the easiest way to keep customers from complaining about "funny noises."
Whizzy brakes, no FD drain plug, what's not to like?