Okay, here's why I asked the question. In January I had a 50cm frame built up and I had a 110mm Nitto stem I purchased for the build. Without looking at me the bike teck told me the stem would be way too long for me. I went ahead and purchased an 80mm stem that I really like. Now I have the Nitto laying around and I was thinking of using on my fixie. I just wondered if the guy thought I was using the wrong size frame or something. Something like, if you're using a stem over 100mm your frame/top tube is too short. Follow me?
As a very broad generalization, a smaller rider will usually use a smaller stem with a smaller frame. There are a whole heck of a lot of exceptions, but I think it's a fair generalization. Conversely, a taller rider will use a bigger frame with a longer stem, again with a whole lot of exceptions.
Anyone who looks at your frame and says your stem is too long is displaying his inexperience, IMO. The stem length is correct when it gets you into the proper position on the bike. The rest is BS.