"But imagine this. A woman walks by - your colleague Bob knows her and waves. You say, "Bob, who was that?" He says, "That's Stacy from Accounting. She has a great sense of humor." Do we think Stacy is great at her job? Probably not."
I don't think that's quite fair. If I'm not in accounting, chances are I don't care if she's good at her job or not (hell, chances are Bob doesn't even have the knowledge to say if she is or is not). On the other hand, her personality is much more relevant.
If I'm in the same department, her boss or coworker, this of course changes.