You all covered it pretty well, but let me put a different spin on it.
I've been considering taking my list of tools OFF my resume because it's nothing more than buzzword bingo at this point. The truth is that if I can't spend a weekend learning my way around a particular load generation tool, my client and I would be better off just picking a different tool (probably a free one).
That said, when I go into an interview, the first thing I tell someone if they start asking me about a tool is...
"If you want to test me on the tool, bring it in, but to me, it's a hammer. Stanley, DeWalt, K-Mart, it really doesn't matter to me - just tell me that we'll have a hammer and that you are willing to replace it if it breaks."
Basically, my point is that if the person you are interviewing is stressing their expertise with one (or more) tools, try to get the person to talk to you about performance testing without mentioning tools and see what you think. Someone who is worth hiring should be able to tell you a compelling story without needing to show-off their tool expertise.
My son is almost 7. I can teach him how to use a hammer, but I'm still the one building the shelves.