NO. Stay out of it. My next door neighbors bought a house w Tweakers, meth sold out of that house. I don't think cooked in there but can't say for sure. I also know that for FIVE. months. there was no running water to that house. With at least 5-6 people there all the time. REO, bought by an agent, fixed and flipped. New neighbors aunt is RE agent. I would think that by now it should all be known but it's none of my GD business.
Now, if that house ever went on the market and I didn't buy it myself, and buyers were mine, I'd tell them everything I'm aware of and strongly advise complete investigation.

  Whatever you say can and will be used against you in a court of Law.   Stay out of it!

Is it your business?  D0 you have a pony in this race?  If the answer is no then the answer is obvious.

Ruh roh! Call the movers!

I would be like you and remain anonymous.

My answer still remains the same. Unless you want possibly go to court and lose your license and profession, I'd stay out of business that is not yours.

I would keep my eyes on my own paper, as they say.

Unless I am representing the seller or buyer in a transaction,  I am not involved. 

I would feel terribly bad but I would stay out of it. 

I'd stay out of it.

Have no clue what you're talking about from your question's phrasing. 

Changing my answer now, and getting 'in the middle' would not be something that I would do.  Again, I don't represent either buyer nor seller, and my answer does not change.  Since the Inspector did not catch 'whatever', maybe 'whatever' is now fixed, as opposed to 'well covered'.  Will read replies below though!

Mind your own business.

Great question and asnwers. Good luck. 

Good answers are here. I hope you find the best one. 

Many great responses.

NO!!!!!!!

One thing about instigating a court battle, you will be identified somewhere along the line.  Why the mask during this intense questioning session?

You are looking for trouble!

definitely stay out of it.....

Nope.  Not my circus, not my clowns.

It is still none of your business.

No.

If there is a significant defect, however well covered it is, the buyers WILL find out by themselves. And then they can decide how to handle it.

Now, IF it is a life-endangering safety problem and IF not telling the new owners could wind up in their death/ultimate destruction, then of course tell them.

What's the defect we are discussing?

No.

I did not see yet the first Q, but it happened to my neighbors recently and they hired a lawyer to sue everyone( seller and the inspector)  and seems they are going to win a lot of money.

No. 

No

Good intentions will get you nowhere. Stay out of it or you will find yourself right in the middle.

I say nothing. I am not qualified to speak on the structure stability. Bending moment, shear and buckling load. If the stress exceeds yild point, I run with my mouth lips tightened.....

No need for Mohl circle, Sigma =Mc/I. I see nothing..... 

How do you know it was well hidden and not repaired?

I am gleaning more about the question from the comments. However, I do not have a clue what you are asking ... therefore I cannot provide an answer to "changing my answer". 

no why would it.. you have no obligation and again where is your KNOWLEDGE coming from? are you an expert on structural engineering? if not and you don't have a report from one you KNOW nothing

If they mention something about it to me, then I will tell them what I know.  I wouldn't bring it up on my own, though.

I tell my buyers to meet their potential neighbors and ask about the area. If I were approached in this way, I'd tell them to have an inspector check out the issue you heard a rumor about.  

If I weren't approached, I'm not sure I'd volunteer anything.  

Not being an agent, my answer may be different than others. I would not be in a hurry to race over and involve myself, but if I became friends with the owners over time, I would eventually mention that I had heard X or that I saw X and am glad that it was repaired. Let them take it from there.

If the agent knew about it and didn't say anything, they should be sued and disciplined.