Where's the leak?

We took Danny to the airport yesterday, sob......  It was nice to see him.  We don't get together near enuf.  It's amazing how years go by and you don't even realize it.  But, he was the same old bro.  Good guy.  He has worked all of his life in construction of some sort.  First with the family business.  Dad put the boys to work as soon as they turned 16.  Then, when Dad retired and dissolved the business, Danny found a similar job and has been working there ever since.  He is now considered the fire and water damage expert at his work.  That's the lead-in for the next part.....  We built this house 17 years ago (talk about time flying!) and we were aware at the time of some of the mistakes that were going on.  Yeh, I worked for the family business, too.  That's another story.  We insisted some corrections be made, and some things upgraded.  I know what "builder's grade" means, and I wasn't having any of that!  Well, 17 years later, our ceramic tile in our kitchen is starting to come up.  What?    Now, enter the water damage expert....  We hadn't noticed that there was a kind of pattern going on.  So, he followed the pattern which led to a couple different things.  Could be a leak in the bathroom somewhere.  Could be a leak in the roof....somewhere.  Could be damage to the subfloor.  Could be condensation....prolly not.  He came up with about 6 or 7 different things that it could be, all of them scarey for work and $$.  He wasn't here long enuf to find the leak.  We know we have one, but it is not obvious, at all!  No water stains, nuthin.  But, the subfloor was "wet", and looked like it had been for a long time.  Maybe ever since hurricane Fran.....  oooo, I digress.  So, now we have to find the leak, fix it, tear up prolly most of the floor, or all, dunno, and check out the subfloor.  That could be damaged, too.  Yikes!  It must be time for me to run away from home!