My friend is an aspiring singer and is determined to pursue this as a career. The problem is I don't think they can sing very well (and I'm not the only one who thinks this). Should I try to say something to them?
Please Do Stop the Music
Normally, I would advocate for total honesty in a friendship, which would mean a very uncomfortable talk between you and your friend. However, in this case, I think you can be spared from telling your friend that he/she sucks at singing because someone else will eventually do it for you.
That someone else could be a talent agent, record label exec or even the guy who runs the open mic at the neighbourhood bar. What I mean is, people who will actually have an impact on the future of your friend’s career will do what they’re supposed to do.
You will do what you’re supposed do as well, as his/her friend. When, inevitably, Jack or Sheila is told that they’ll never be a singer, you will be there to pick them up off the floor, buy them a few drinks, and sit through some sad karaoke sessions. Leave the real work to the professionals.