Consistent Glomarization should be feasible

With close friends or rationalist groups, you might agree in advance that there's a "or I don't want to tell you about what I did" attached to every statement about your life, or have a short abbreviation equivalent to that.

This already exists, and the degree of “or I’m not telling the truth” is communicated nonverbally.

For example, when my wife early in her pregnancy we attended the wedding of one of her friends, and a friend noticed that she wasn’t drinking “her” drink and asked “Oh my gosh, are you pregnant!?”. My wife’s response was to smile and say “yep” and then take a sip of beer. The reason this worked for both 1) causing her friend to conclude that she [probably] wasn’t pregnant and 2) not feeling like her trust was betrayed later is that the response was given “jokingly”, which means “don’t put too much weight into the seriousness of this statement”. A similar response could be “No, don’t you think I’d have immediately told you immediately if I were pregnant?”, again, said jokingly so as to highlight the potential for “no, I suppose you might not want to share if it’s that early”. It still communicates “No, or else I have a good reason for not wanting to tell you”.

If you want to be able to feel betrayed when their answer is misleading, you have to get a sincere sounding answer first, and “refuses to stop joking and be serious” is one way that people communicate their reluctance to give a real answer. Pushing for a serious answer after this is clear is typically seen as bad manners, and so it’s easy to go from joking around to a flat “don’t pry” when needed without seeming like you have anything to hide. Because after all, if they weren’t prying they’d have just accepted the joking/not-entirely-serious answer as good enough.

I like the mixed strategy. You don't need to be perfectly consistent, only frequent enough that it carries very little weight. You need to obfuscate some multiple of actual cases of suppressing data, but some fraction of questions that are asked.

Most of the value in this kind of thing is _not_ information-hiding. The fact that the question is asked in the first place indicates a pretty high credence already of the asker. The point is deniability - the questioner doesn't have usable proof of the activity, so can't act on it. Deniability doesn't take perfection by any means, only a bit of uncertainty.

With close friends or rationalist groups, you might agree in advance that there's a "or I don't want to tell you about what I did" attached to every statement about your life, or have a short abbreviation equivalent to that.

This doesn't come up with close friends. This is only for groups and more distant power relationships where deniability matters.

In my culture, we don't put much weight on true-but-information-limiting statements. We do spend a fair bit of effort on pedantry and unnecessary precision, though, so it's fun to talk about this regarding "safe" topics. But that's mostly a game and a chance to quote Futurama ( https://www.youtube.com/watch?v=hou0lU8WMgo). Topics we actually care to keep hidden, we simply and directly lie, in whatever way moves the attention somewhere else.

How honest are you really being if you're coming up with silly logical scenarios to avoid answering a question truthfully? I just don't see the point of being "technically honest" when you don't want to reveal something? The only people who say, "I can neither confirm nor deny such and such" is when they are on trial and have a right against self-incrimination--not when they are talking to their friends.

So this all seems silly and unnecessary. If you don't want your friend to know what you did, just change the subject or lie about it. Or tell them, "I'd rather not talk about it." Let's say I stay up doing cocaine with a male prostitute all night, but I don't want to reveal this to my friend. If I say, "either I did or I don't want to tell you" now you've created some suspicion which could involve some unwanted attention or scrutiny into your affairs, such as pressing forward with follow-up questions, or unwanted office gossip about your late night activities.

FRIEND: Did you get to sleep early last night?

Just lie and cover up the reason why you're really tired.

"Yes, I went to bed early, but then woke up at 5AM and couldn't get back to sleep."

Deflect

"Sure, how about you? Or did you stay up watching binge watching Netflix again?"

Subject Change:

"Oh hey! Can we talk about that upcoming dinner party?" (they were just making small talk anyway, so swap to something more important.)

Why lie on the d100 coming up 1 instead of "can neither confirm nor deny"?

The fact you rolled the die (seems like it) is revealing.

While consistent glomarization is feasible, one must consider the social context of doing such a thing. If you're with close friends or within the rationalist sphere, then your compatriots will understand you. But outside the cult, per se, you need to be careful. Honesty is important, but sometimes, a white lie is better than a truth. For example, if your friend asks you about a question you do not want answer, it's probably more respectful to respond with a non-answer or a joke answer than to say "I will neither confirm nor deny the answer to your question." 

Glomarization can be frustrating to deal with. Thus, it's probably better to have a policy of no glomarization than a policy of consistent glomarization. Because consistently glomarizing will offend people not versed in the rationalist sphere, and code-switching will lead to a contradiction of the original premise.