The most likely place you will find bad sound is in amateur theatrical productions – school plays, children's dance shows and the like, so I'm not actually talking about professional sound. Even so, it doesn't hurt to aspire to professionalism in my view. I'll give you an example…
I was watching a ballet show performed by youngsters of all ages to an audience of 1000+. Every time the compere came on they would either speak into a silent microphone, ask if the mic was on, blow into the mic or tap it. That's bad sound.
There are two elements of professionalism in this context. One is to pull the fader down when the mic isn't in use. An open mic in a live show is an open invitation for profanity of some kind to reach innocent ears. Like mine.
The second is that if you are the sound operator, then you should know that when someone walks up to the mic, or comes on stage, mic in hand, you have to be ready to push that fader up at a moment's notice, or no notice at all.
If the sound operator doesn't realise that this is an absolutely top priority, way above gasbagging to the other technical crew on the intercom, then they are not doing their job properly. This applies whether or not they are being paid.
Any sound professional would of course recognise the importance of this. Any sound non-professional will wonder whether it's really all that important.
But what is most important for anyone who seeks professionalism in sound, for themselves or from the crew they work with, is that people need to CARE about sound. When that happens – truly happens – everything else will start to fall into place.
Well that's the moral. But what about the poor compere? The compere of the show should be able to talk into the microphone at any time, without having to test it, and be CERTAIN that it is going to work. Without that confidence, the show is going to be a pretty rough ride for everyone.
P.S. Since writing the above I attended a school music concert that demonstrated my point amply. Apart from some guitars and the announcement mic, the concert was unamplified. One of the teachers acted as compere and made a dozen or so announcements during the course of the evening. On not one occasion was the mic live when she started to speak. Several times she checked the switch on the mic and finally she gave up using the mic altogether. Apart from that, the concert was a delight. It's a shame that the worst feature of the show had to be the sound.