How can you avoid the 'exit interview'? If anyone cared, they would do something to gauge worker's feelings of the company before they quit!
Also, how can I be sure when HR is called for a reference they don't badmouth people who leave because THEY were toxic? Our employee handbook doesn't say their policy of what they will say when asked by a potential new employer....most employers have a policy, clearly stated, that they will only confirm job title and dates of employment - my workplace tellingly doesn't even have a policy!!1