Gene Quinn's discussion of hitch-mounted toilets at IPWatchdog.com leads to a valuable point: just because something is patentable does not mean it should be patented.
Inventors often fail to recognize that companies and investors aren't interested in inventions but in solutions that improve people's lives. If your patentable invention isn't a step forward with practical value, why bother?
Outside eyes are helpful here. Inventors love their work, naturally, but what matters is how others react. If the problem being solved is one that people don't care about, or if the solution is too complex and awkward to be useful, the market won't be interested, no matter how brilliant your voice-activated dental floss dispenser is. It may be patentable, but should you patent it? Is it worth the expense? Get some market input and outside expertise to help you make that decision before you spend your savings on costly patents.