Is "crooner" old-fashioned and humorous?
Solution 1:
Yes, it is an old-fashioned term...think Bing Crosby, Frank Sinatra, etc. But it is occasionally applied to current artists, such as Michael Buble, probably because they remind listeners of the classic crooners. (I believe the term is used only for male singers.)
I don't think the term originally had the connotation of humor. However, crooners sang popular songs in a syrupy manner (in some listeners' opinions), and their style of singing has been parodied in recent decades. See Saturday Night Live's sketch of Will Ferrell as Robert Goulet (a crooner).