Tristan, you will only run into more and more of these as the industry continues to evolve using these type of coatings. The focus has been on durability and not removal and maintenance. They may not be easy but if you charge accordingly you at least get paid for your work. The trick is in identifying these coatings when doing your estimate. I always ask if they have the old can, most do, or if they know what was used. Also, it is important to word your proposal correctly. I use terminology like, "not responsible for work previously performed." Then there are lines that get checked and a price added to original price like "This job may need a second stripping for an additional $____" and "This job may need sanding for an additional $____." This way you can cover all bases. You can either include these prices in your proposal if you know they need to be done or put in a separate amount to cover your butt. I have never had an issue doing this.