What's wrong with this picture?
This picture comes from the front cover of the second edition of Sound Engineering Explained by Michael Talbot-Smith. There's nothing wrong with the book, but I have to wonder how this photo made it through the editorial process (I suspect the author was unaware, and probably horrified when he first saw it).
The picture is plainly posed either by models, trainee engineers or amateurs. The singer is obviously giving a spirited performance, but he is holding the microphone stand! There is never any reason to hold the mic stand in the studio. It will lead to significant low frequency noise coming through that will be very difficult to filter out later.
There is only one exception to the rule of not holding the mic stand, and that is in live sound where the singer is using the stand as a 'prop' to aid his or her performance.
There are only two reasons to hold the mic itself without a stand, one is in live performance so that the performer can be mobile, the second is in the studio where rap performers feel more comfortable holding the mic and therefore do their job better.
Otherwise the mic and stand should be inviolable.
The other problem with this picture is a little more subtle. Take a look at the engineer. She is partially hidden by what seems to be a monitor so she is probably less completely covered up than she appears to be. In normal life, this would not be a problem of any kind - she'll look good and presumably attract the kind of attention she wants.
But in the recording studio she could easily find herself working with a female artist. One of the golden rules of studio etiquette is that you should never compete with the artist - you are never more talented, never more clever, never more witty and certainly never more cool.
And when it comes to dress sense, it's good studio etiquette just to tone things down. The rules of everyday life do not apply in the recording studio. An awareness and acceptance of studio etiquette is something that every studio manager prizes most highly in their employees.