So when I'm doing front, side, and rear delt flyes my shoulders make this crunching noise every single rep. It's not necessarily painful but it's uncomfortable I suppose. Did I visit snap city and not even realize it?
Don't listen to these guys. The crunching is normal per se, but only because the average person doesn't do mobility exercises.
You can keep going and hope not to get a shoulder injury, or you can deload the weights and work on increasing your shoulder flexibility.
Used to have the same thing, but now that I've done mobility work, it's gone.
Could be a sign your form is off. Shoulders are naturally designed to be raised in front of you. If you are raising too far to the side (such that your body forms a straight line from arm to shoulder to chest to other shoulder to other arm) you could be asking for an impingement.
I had the same problem for well over a decade OP.
It is the sound of the tendon moving awkwardly over the bone -- it causes a popping noise and a weird sensation in your shoulder if you focus on it.
9/10 doctors wont do anything because nothing is technically wrong.
Nonetheless something in the past happened to your shoulder to cause the tendon to move in such an awkward way.
The minute you have a sharp pain in the shoulder, you know there is a tear or partial tear.
Source: me -- I had the same problem, eventually tore the shoulder. Had to get surgery, but now at 100%. They also fixed the popping noise too at least.
Forgot to mention me tearing the shoulder was a separate issue from the popping noise.
It was just while they were sewing the muscle back together or whatever it is they did, they also managed to fix the unrelated popping noise.