This “European” treatment promises to reduce cellulite in problem areas by covering them with clay and stimulating the muscles with electrodes, but cruise ship spas offering it are known to tempt you with one session ($159), then recommend a series of three for ultimate effect ($339). And then you'll get a high-pressure sell for expensive after-care serum to maintain and improve the results.

It's easy to fall for this pass if your idea of bliss is a daily jetted-tub soak or steam in the sauna — just be aware that most cruise itineraries with daily port calls leave little time for the spa, so you may feel you’ve wasted $119 to $159 if you only use the pass once or twice. The exceptions: transatlantic and repositioning cruises, when you have multiple days at sea to get your money's worth out of the weekly pass. Otherwise, consider a daily pass and set aside enough time to really enjoy it.

We love a good facial. But when the price reaches $325, as does the 24-karat gold leaf facial offered by several cruise lines you might want to consider whether the benefit matches the markup, especially when most other facials are less than half the cost.

The mani-pedi is perhaps the most popular rip-off at sea, costing on average about double what you’d pay back in most home towns. For great-looking hands and feet, get your nails done before you leave for your cruise.

Yes, many cruise ship spas now have cosmetic-procedure-trained doctors onboard offering Botox, Restylane and Perlane injections in a Medi-Spa. But we prefer the idea of getting these treatments close to home, where you have access to the doctor for follow-up treatments. The same goes for single-treatment tooth whitening, which can cause sensitivity and make coffee, red wine, and other beverages off limits for a few days of your cruise.

“Free” makes these seminars sound tempting, sure. But these sessions are usually nothing more than a hard sell to sign you up for a series of onboard treatments, including Ionithermie and Medi-Spa injectables.

In your post-massage euphoria, you might very well be susceptible to your therapist’s persuasive touting of an expensive skin-care regimen. Save yourself the hassle by making it clear from the onset that you will not be buying products.