I have a Toastmaster TSC15 1.5 Quart Slow Cooker.

Most of the really dangerous products don't even have a warning on them. Also, the product should respond to some security standards and to have passed the pre-market tests. I found a review from a guy on Amazon, he is still alive and happy four years after purchase. :) But other two people are very disappointed. And yes, theirs are also without temp gauge.
Your duty as a good citizen, however, is to notify the respective authority, so that based on your signal they can withdraw the product from the market, if it is a health threat. Meanwhile you can put it temporary on the shelf, or ask for a refund if applicable.