Joe Biden has - PRIOR TO TARA READE - never been accused of sexual assault, despite a decades-long career in government. He's been potentially a target that whole time, but nothing comes out until he runs for president. It's not a coincidence.
All the women who have worked with Biden throughout his career vouch for him. He's regarded as a champion of women's rights.
I'd say he has credibility.
I'll also say that, unless I'm misremembering, Harvey Weinstein had a decent amount of credibility until all the accusations came out. But we all know he's a bad guy now.