"Ain't" is pretty universally viewed as informal language, and therefore out of place in formal communication. Until just two years ago, "whitelist/blacklist"

"Ain't" is pretty universally viewed as informal language, and therefore out of place in formal communication. Until just two years ago, "whitelist/blacklist" was completely normal language with no racial connotations, and I would wager that it's still viewed as completely normal by the vast majority of people. However, in just the last two years, people of a certain political persuasion in the US have decided to make these phrases into an issue. If it is critical for you to communicate and come off well to a relatively small subsection of upper-middle-class liberal Americans, then these suggestions might be helpful. If it is critical for you to communicate with fundamentalist Evangelical christians, then a different set of suggestions might be helpful. I view the two situations in exactly the same way. However, if you're just writing for a generic audience, then these suggestions come across as unwelcome proselytizing.