fwiw I have a slightly different view on this which is that if it’s a high impact/high profile hire you should do anything and everything to get a full picture of what they’re like. In particular if there is a gap in their CV or there’s a company they worked for briefly that they don’t talk about, it’s in your interests to find out why. I know it’s a bit controversial, and I should also caveat this by saying that I worked in New York for 2.5 years where people do things a bit differently, but I have got backdoor references on candidates that I was thinking about hiring and was really glad I did because off the back of that I didn’t hire them and it was one of the best decisions I ever made.