Gloria was such a clicker! It certainly was not in any way related to stress/anger/fear! She was a Syrian and she only clicked when she was very happy, like when snuggling or when eating her favorite treats. She could click so loud it was like a cat's purr, and when we clicked our teeth she would click back as if having a conversation about how happy she was
She was an extremely vocal hamster and we communicated with her by mimicking her noises for happy or mad to communicate yes and no. It worked very effectively
I miss my little clicker <3