Unless I knew the referee
Or knew someone I could trust who knew them, I don't trust them. Make sure you get some team members in on the interview. A few open questions, about processes likes and dislikes for tools, interacting with "customers". More likely to get a definitely not than a definitely yes, but it all helps.
Tick list questions should be closed, and they should be done before serious amounts of resource are put into interviews, where 99% of the questions should be open.
I've got jobs before where I didn't actually know the language they wanted me to develop in, I knew a heck of a lot about the domain though and about how to develop. Attitude, then skill then familiarity with some tool or other. That's where the buzzword bingo boys keep going wrong they assume the first two and are incapable of understanding the relevance of the last.
