I have had my K-5 with me all over the theme parks in Orlando FL and have taken it with me on every single water ride I went on. For two days at Disney it rained, and I was pretty much the only "idiot" fool enough to have my camera out in it(well that is how folks were looking at me...like I was an idiot fool willing to destroy my DSLR)
I am happy to report that the camera performed flawlessly in every water related condition I put it through. Yes I was testing the capabilities of my camera, why? because I would rather it give out now, instead of down the road where I have it out shooting something really important and it dies on me then.
One of the main reasons I got my K-5 was for the advertised weather sealant capabilities, I needed a camera where I can take it and not have to worry about getting it wet, full of sand and dust. I am the type of person who prides himself on testing out the capabilities of a given item, however once I am sure that it performs as promised, I tend to back off on the testing phase and actually start to "baby" my equipment as much as I can although I am still rough on it.
I also constantly wiped the whole camera/lens/grip down every chance I got because even though it is weather sealed I still wanted to make sure (once it was tested) that I was really not intentionally giving it a reason to fail on me.
Just like the OP I will not hesitate to show someone the abilities this camera possesses of weather sealing and will dump a glass of water on the camera......I've seen me do it.
His camera shouldn't have leaked with just 1/4 cup of water splashed on it, and Pentax really should IMHO offer him a new camera as a replacement, and if not then they shouldn't advertise their equipment with images of them throwing a lot of water on a camera body.
I have used Pentax gear all my shooting life and it has NEVER let me down, hope for the OP they make good.
Disclaimer-For those of you who are calling "BS" to my claims of taking my camera on the water rides AND using it while on the rides, I hope this clears it up-
I must have clicked off around thirty shots coming down that hill, I had the camera set on continuous high speed shooting and this is the "wettist" shot, we were all SOAKED from head to toe when we got off this ride along with the camera......I just wiped it off and went on my merry way in the happiest place on earth.