As with any language, it depends on many factors. Who is saying What, When it is being said, Where it is, Why is it being said and How.
Anyone being nice has a pleasant tone, anyone in a bad mood will sound bad...

A happy guy, making toasts, after work at a bar, because he is a new father, smiling is a good sound.

Bitchy Assistant Manager, bitching at the help, at the start of work, because she has problems dealing with others, like a bitch is a bad sound