It is a great time to buy in Tucson. Prices are low, and so are interest rates.
For this particular property, there was a free standing shed built in the back yard, and also a covered patio. It is up to a buyer to investigate further to ensure that necessary permits were obtained for these items, to avoid any potential fines or penalties when they take over the property. If permits were required and obtained for these improvements, no problem. If permits were required and not obtained, and a buyer takes on the property without those issues being resolved up front, then they take on the potential problems that might arise.
Regarding the polybutylene plumbing disclaimer: Many homes built prior to 1995 had this type of plumbing and/or fittings installed, that sometimes have resulted in leaks and flooding damage to homes. It is unknown if this home contains polybutylene plumbing. Since it was built prior to 1986, if it is a concern to a buyer, they should have the plumbing inspected prior to purchasing the property.
It is wise of you to take notice, and ask questions. Having a good Buyer's Agent on your side who will help you to investigate the home that you are considering to purchase, is also a very good idea.
By the way, this home is currently listed as "Active Contingent", which means that there is currently an accepted offer on the property, and the buyer and seller are working through the process to move toward close of escrow, and completing the sale.
If I can help further, please don't hesitate to ask.