I don't have so much experience interacting with recruiters/hiring managers. However, every time I've let some frustration show at work, in the moment I felt vindicated and righteous, only to feel like an ass about 24 hours later. Normally when I feel the need to vocalize a frustration, I try to write down or remember why I'm frustrated, but wait to actually action the communication until I'm calm. Goes a long way to focus on solving problems, without identifying people as the problem.