KindRose... yes, that is a dilemna. Wish I had an answer to offer but I don't.
Waxed paper is opaque, as is any other kind of wrapping paper you might look at. I understand your concern that people taste and buy with their eyes long before the food is actually eaten. Even a high-quality photo or display card on a label probably will not be as effective as seeing the exact samdwich being bought.
I don't eat many pre-made sandwiches for just he reason discussed in this thread -- one too many soggy sandwiches in the past. I look for quality but condensation is really what I'm looking for when looking at pre-made sandwiches -- one hint of sogginess and I'd rather go hungry than eat it.
This has been especially prevelant with those sammies in the triangle packaging in vending machines. I sometimes think that they have some secret at the sandwich factory, like filling the packaging with inert gas before sealing it up. Not that they have ever been good, but I've had some factory-made sandwiches that have saved me from starvation. :) But often it seems like a handling issue, where the vending machine guy lets the product sit in the sun and then puts them into a cool machine. No matter the source of the sogginess though, soggy bread makes me gag.
To be honest, I also look at the preparation date. More than 2 days ago... and I'd rather go hungry.
But, somehow, a "healthy natural" sandwich packaged in plastic just doesn't seem right.