I would agree with the fact that you should be cautious while in interview, because word CAN spread out - that's the reason I try to be polite even when I know the other guy is just wasting my time by telling me he has a job opened while in fact he's just filling up his CV bank for later.
On the other hand, it CAN pay up to actually go out of the box in an interview. For most people, an interview is just going through the rote questions and the predictable answers, an exercise in pretending and checking the boxes and above all not give a "warning signal". It makes for pretty boring interviews.
As such, I've found that, as long as you're not provocative, being frank and honest freshen considerably the interview and gives you massive "rememberance points". In a sea of half-truths and calculated responses, being able to be and feel candid is something that gives quite a bit of goodwill, and it can even be actually better to be "less than ideal" to convince a recruiter - because it shows you as playing cards on the table, so no "bad surprise" and you feel like someone people can trust and depend on. For example, in my job I was asked if I was ready to move sometimes, possibly far away (missions in other cities and some in China or South Africa). I downright said "no way, I can do with a few short trips in local cities, but no long-term or international moves". It certainly wasn't what was expected as an answer, but it was consistent with what I said previously (that I think about my well-being first and look for a good working environment) so it gave me "trustiness cred" and "this guy will tell us if there is a problem instead of letting it fester and cause hidden problems".
It's important to It WILL NOT opens up a job for you if you aren't fit for it, it CAN shuts you down from a job if your owned imperfection can get in the way. It's not a miracle method. Also, it's VERY easy to go from "honest" to "flippant" if you're pretending instead of it being a core part of your personality. Sincerity and the ability to convey it is paramount (and conversely, being able to soften your rough edges into something that can look workable with instead of "this guy is going to be a PITA").