There's a very obscure search we have been ranking well for for years. However, just in the last few days, a "did you mean" has appeared above our listing which refers people to other sites. It doesn't affect us in terms of traffic as the term must receive about 10 searches a year, but has just made me curious. How does Google actually determine when to offer a "did you mean?" and which alternatives to suggest? I tried doing some searches on the net to see if anything's been written about it, but couldn't come up with anything. Cheers.
Google's spelling mechanism must have decided that your spelling is a misspelling. It probably means that the word is not found very much on the net, or that maybe it's not a dictionary word.