Just some food for thought here. The ASPCA does not believe that reptiles should be kept as pets at all. http://www.aspca.org/adoption/adopti...c-animals.aspx Do you REALLY wish to report something to them that will just add fuel to their animal rights agenda?
Yes the snake looks starved and dehydrated and it should NOT be on the sales floor, but it's impossible to accurately access an animals health from a picture. As someone who has volunteered for a reptile adoption program for over 10 years, I've had ACTUAL experience working with snakes that looked like this, and no this is NOT the worst I've ever seen. Some have been turned around with nothing more then a little TLC and some simply didn't thrive no matter what was tried. Just because something LOOKS bad does not mean it's at deaths doorstep.
Going in and making demands of the owner will do nothing more then fill THEM with righteous indignation as they show you to the door or call the cops. Having a rational discussion about why the snake should not be on the sales floor, why having a sickly animal on display reflects poorly on their business and giving them advice on how they can better care for it will go MUCH further then stomping around and making demands. Believe it or not, pet stores are not gold mines, people will generally open a pet store because they actually like animals. They just may not have experience or knowledge of of how to properly care for every species they carry. If you can convince them of your genuine concern and willingness to share your knowledge they may even thank you for helping them out with their problem.