The scale of the rubbish you refer to is certainly a new one on me, and we have been going to PP every year since 1999, sometimes 2 or 3 times a year and sometimes long stay in the winter. Granted you will see the occasional plastic bag and cig ends, but the local council are meticulous about cleaning the beach and the whole area every day. The Mallorca government employs 12 boats that patrol the island constantly picking rubbish out of the sea, why they need to do that is indeed a disgrace but it seems that the people who drop the stuff are everywhere these days. You will not escape this stuff anywhere, I know from experience.
You refer to Menorca, we've been there and (personal, subjective opinion), it does not hold a candle to Mallorca, especially if you get out and explore the island.
A good tip in PP if you are staying in self-catering accommodation, all of the larger hotels run a nightly floor-show and for the cost of a drink you can sit in (in fact if you don't want the drink simply sit in and say "no thanks" to the waiter, they'll think you are just another hotel guest). The town abounds with nice restaurants and bars where you can pass an evening chatting or people-watching or listening to entertainment. I'm biased, I like it.