What, no "Culture: Singing" category?
Due to a resonance effect within a person's skull, average people who sing tend to think their voices sound better than they actually do (and often have trouble recognizing themselves in a recording).
But probably almost everyone who tries this will think their
voices sound awful! And as for what others will think about such voices ...!!
Sing "Ahhhhh" in a normal medium tone. Notice how you are breathing out while you do that.
Now try it in reverse, sucking air into your lungs while using your vocal chords to try singing "Ahhhhh". It will certainly sound different!
If you can withstand the sound of it, then you will find it will take some practice to sing more than a few notes in reverse. Try any popular song and see for yourself. (And, please!, try to avoid choking on your saliva while doing this!) Now imagine a whole choir of HalfBakers singing this way in a bar...expulsion becomes a near-certainty, of course!
Anyway, as indicated in the subtitle, it may take a truly remarkable ordinary singing voice to sound even halfway decent, singing in reverse.
It has occurred to me that you can use this vocal manipulation technique when talking on the phone to telemarketers or other worthy recipients of the awful sound of it, to disguise your voice. Have fun!