Be sure to advise them, in writing, in the Rental Agreement, to NOT use abrasive cleaners or scouring pads.

lol It's not an abrasive question, just wondering why you used this exact phrasing to make a point.

Like @Russell Brazil and @Cody L. and many others said you are asking a question and then acting like an expert on the back end but your responses do not have anything to do with your actual problem and you are coming off abrasive to good advice.

If you look at my posts I'm sure you'll find that I do not typically post abrasive or impolite responses.

Rip off the bandaid...change everything now, using a new cast iron/porcelain tub and ceramic tile surround for a job that will last the next 30 - 40 years.Reglazing, IF done properly, can last 5 - 7 years if you are lucky and the Tenant never uses abrasive cleaners or is otherwise rough with the tub...washing car parts in it etc.

@James Wise is well known, and has a hugely abrasive personality that can and does rub a lot of people the wrong way......but when it comes to business and real estate....he is absolutely 100% brutally honest.

Thank you for the comments (even though they were a bit abrasive).

You will need to delaminate glossy surface faces with the abrasive side of a simple scrub sponge.

@Jay Hinrichs-Thank you for your rather abrasive comment(s).  

I also bought a $100 wet tile saw and some diamond abrasive pads to polish the edges.