Value is usually based on demand. While a defective piece of Pyrex may be interesting to some collectors, the number of people who want defective items may be low enough to reflect a low demand. Most collectors prefer pieces that are in the best condition with no scratches, chips, stains, or other damage.
Defective Pyrex does appear on some sales sites. Check eBay but look at the sold listing prices in Advanced search. Selling through an online site would be the best way to sell as it reaches a wider customer base than, say Craigslist, or selling through consignment.
Keep searching for online sales to get an idea of the value of misprinted, or defective Pyrex. Sooner or later you will spot some. I found a few completed sales on eBay rather quickly.