I have to agree with Showcat, communication is the key in finding out if you match with your potential cabin mate.
As for myself I prefer to pay the extra money to go solo in a room this is MY VACATION and will like to treat it as such.
With my first cruise under my belt I feel that I know what I want out of a cruise and use that as a basis for any future ones. I wasn't looking for romance in my first cruise though the women outnumber the men on the cruise I only found 5 that I was interested and they were being fought over by the men on the group. I must give a note to single guys do some research with all the companies that do single cruises and ask alot of questions, if you are looking for the Swedish Bikini Swim Team you will be disappointed most of the women (and men for that matter, for you women) will look like the people you see in your local Walmart. As with the first my second cruise I will not be looking for anyone but will have a good time.
I don't have horror stories to tell you but alot of single women were complaining that there were not enough men at the table but it was more the cruise ship fault than the single cruise company.
Overall, it's the luck of the draw that you will find a roommate you will get along with but again, enjoy the cruise first.