Good meetings tend to happen when the person who organizes the meeting has a specific request with a specific deadline. Someone is asking for help.

Telling traits of a good meeting is clear objectives, open lines of question, honest debate about underlying assumptions, opposing (and evidenced) points of view, moments of (thinking) silence, collectively-made decisions ending with the exacting delegation of concrete tasks. Including the possibility of a collective decision to abandon the work with no further tasks. Good meetings are invaluable.

Bad meetings actually have many of the same traits as good meetings, but lack the clear decisions and follow-up tasks. Someone is still asking for help. Honest debate happens but do not progress the work very far. Smart things are said but without committed next steps. Bad meetings are frustrating, but often still have value because they stem from good faith effort.

Bullshit meetings are when everyone shows up already confused.

They show up for the sake of showing up.

Someone isn't asking for help.