While distribs and exhibs wrestle over the costs of disposable 3-D glasses, reusable glasses bring their own issues, and the Cannes festival is about to bring them front and center.

The fest, going green, will use a reusable glasses system from Xpand in five theaters. But organizers chose not to install the cleaning machines for the glasses that some theaters use.

The gala opening-night screening of “Up” will have brand-new glasses, right from the box, but thereafter the box office will give patrons sanitizing wipes and ask them to clean their own glases.

Laura Peralta-Jones, VP of sales and marketing for Xpand, says, “We’d just as soon they be responsible for cleaning their own glasses, because people in Europe are accustomed to that.”

But, acknowledging fears over the spread of swine flu, Peralta-Jones left open the possibility that Xpand teams might step in to clean the specs.

The spread of illness via dirty glasses raises liability issues for theaters, which is why many opt for cleaning machines.

And while there are anecdotal reports of customers encountering dirty glasses even at the Grove multiplex in Los Angeles, Dolby VP John Carey doesn’t think such problems will impact auds’ support for 3-D, as long as they remain isolated.

“When you go to a bar and get a dirty glass, that doesn’t put you off drinking beer,” says Carey, “You just send it back.”

And he says dirty glasses are less of a complication for Dolby and Xpand than theft and breakage.

Theaters incur costs stopping patrons from walking out with them, especially if they’re used to disposable glasses. With Dolby glasses running around $27 a pair, a few lost pairs can really hurt a theater’s bottom line.