You have a good point. If you are seeing water in your oil (during this test)then you should be seeing fuel in your oil (during normal running conditions) or vise versa seeing oil in your fuel. The reason I bring this up is if you are getting carbon deposits then it is probably coming from two areas...either improper combustion (too rich) or oil leakage into the cylinder. If oil is leaking into the cylinder then as you said you have some pretty serious problems.
Also, oil and water don't mix, right?!? Wrong, oil will dissolve into water up to 200 ppm (parts per million) and you won't be able to see it with the naked eye, depending on what type of oil you are talking about. Even at this small amount it is just as dangerous as having standing water in your oil. Here is an interesting article about water in oil. Once you get past the trade jargon it has a lot to say.
http://www.noria.com/learning_cente...eid=192&relatedbookgroup=ContaminationControl
The reason I say to use Sea Foam is that you are guaranteed to not have any water ingression issues as Sea Foam is a completely combustible material. But if you do go with the tried and true method of pouring water into your carb, then you should change your oil and oil filter just in case. We're talking about $20 or so for peace of mind. Also, don't over do it. Just a little water at a time is OK. Water is a non-compressible fluid. If you pour too much in there and it doesn't all flash to steam then you have the possibility of blowing out a cylinder wall. Beer is a different story. I guess at least it has some combustible properties!!
I know the cylinder wall blowing out is pretty far fetched, but I have seen it before. Not on this process, but one of my friends had a problem with coolant ingression and blew out a cylinder wall when the cylinder lost ignition. Not a pretty site!
Good luck with either option.
Scott