Just for fun:A "real" cooking dilemma.

If you're prepping apples for a pie and you find a worm in one of them, what do you do? (If you answered "throw the apple away", you didn't grow up on a farm and you haven't ever worked in a restaurant kitchen.) The only time a worm is a real issue is if you find half of one in an apple you're eating.

Assuming the stew was up to temp, any bacteria would have been long since dead by the time of discovery.

Informing the guests of the situation would only cause them unnecessary grief. If the situation ever comes up, you have my permission to toss the critter and allow me to blithely continue my meal without passing along information lacking any practical value but which would leave a bad taste in my mouth.

Would the lizard be clean? Would it be harboring diseases?
Did the guests ever find out? Did anyone get sick?
I'd have snatched up all the plates and dumped it -- but explaining this would be awfully hard!

Some people would argue that protein is protein. And I guess it would depend on the kind of lizard - vegetarian or insect eaters? Here is a recipe for cooking lizard.
http://www.gourmet.com/recipes/1940s/1949/10/fried_lizard