This video from AT shows what can happen to venue (or hire!) mics from one night to another. Metal singers love to use their hands and arms in the show – and that means storing the mic somewhere: in their mouth, armpits, between their sweaty legs, wherever is easiest at the time!
That’s all well and good until the quiet jazz singer on the next show wants to get up close and personal with the mic grille. Quiet singers obviously need to be closer to the mic, and the last thing you want when you do that, is to pick up sweat from last night’s metal band, lipstick from the last diva act, and dried up spittle from last week’s grime MC, all congealed together on the venue mic’s grille.
The last thing I’ll say on hygiene is that a singer’s voice and throat is their instrument, and their talent. A cough, a sore throat, or a chest infection can mean the difference between earning a solid living or having a hungry week or two!
Quite apart from any hygiene issues, every type of mic has its own sound – and so does every voice. There will be a perfect match for you, somewhere, and it pays dividends to spend the time to find it. Your voice may really suit an SM58, a beta57, e945, m88, a D5, or something else entirely. Every engineer has their preferred “go to” mic; but a pro singer will walk into a venue, announce that they have their own mic, and ask if it’s OK with the engineer if they use it. Most engineers (as long as it’s a recognised, quality brand) will thank you for saving them time EQing your voice – and you’ll know that you’re getting the best possible sound.