I've always just been straight with my employers whenever it hasn't worked out and I've decided to move elsewhere. That's not to say that there isn't a need for finesse.<p>I actually ended up going back to one employer after a year or so, when it turned out that they recognised that my criticisms (primarily focused on unfeasible expectations w.r.t. work-life balance and pressure on teams to deliver) were valid and took major action to flip things around. Whether they recognised the validity of my criticisms because of what I said, or simply because of more people leaving, I cannot say. I don't remember any conspicuous absences of familiar faces when I returned, so I like to think that I was actually heard.<p>As with any form of diplomacy, there is an art to the delivery. If you're going in with criticism, do so with well-reasoned argument and reference to something provable or better yet numerically presentable, and point out how the criticisms negatively impact <i>them</i> as a business, rather than simply saying that you didn't like [x] or wouldn't have to do [y] at competitor company [A].<p>And for heaven's sake don't make it personal -- I mean, this isn't something I've done, but it seems pretty basic that getting personal is a no-no.<p>For example, if <i>you're</i> moving for a better salary, highlight the fact that they're lagging behind in industry sector [P], and as a result you won't be the only one leaving. If they want to retain talent, they must reimburse the talent competitively.<p>Contrary to the beliefs of some, managers <i>are</i> people, but they don't always think like people -- they're effectively paid to not think like people, but rather to think like a business, to embody the needs of the business.<p>As a result, human considerations can take a back seat, they can be reluctant to react to change especially where it involves <i>spending</i> money, and they can ignore facts because they haven't been the subject of a pie chart. Explain something the right way, however, and you can affect positive change.**<p>As others from the UK have said, references are immaterial. I've never had anyone check my references, and I know this because when I got started in software dev 10 years ago, my references were entirely fictional.<p>** sometimes