The fault in each musical instrument.

[RuiAce]

Let's comment.

For the piano, it's the inability to carry your own instrument with you and hence you're always forced to adapt

I've heard of some saliva-related problems with some woodwinds?

[TheAspiringDoc]

The cork connecting clarinet segments always seems to break 😭
And yeah you should regularly clean the mouthpiece ..

[sweetiepi]

Sore throats tag render you unable to sing

Vocals count, right? 😂

[katie,rinos]

Clarinet: Reeds are around $40 for 10, and although they all look the same some work better/last longer then others.
Trombone (my brother plays): Sounds terrible (like farts) when you begin to play.

[chooby]

Trying to warm up both vocals and brass/saxes in cold weather

[Springyboy]

Trumpet : The valves keep breaking down so you always need to apply some oil on to it after a couple of goes. Also it's pretty heavy to carry still, not as light as a flute.   

[AngelWings]

Talking of flutes, it's surprisingly easy to dent it. Unintentionally, of course. Cleaning is also not easy, since you can see every fingerprint on it!