As a Bulgarian I know few things about Poles and Poland, aside the very basics of Polish history
Basically, the same can be said about a typical Pole's knowledge of Bulgaria. Here are some of my "encounters" with Bulgaria.
1a. Władysław Warneńczyk is known in Poland mostly as a Jagiellonian king who died at Varna trying to fight the Turks (his military expedition was a kind of political mistake, however, as he seems to be largely manipulated by the Vatican against the Polish interests). At present, he has become a 'fashionable' figure again as some people say he had not died at Varna, but was rescued and later became father to Christopher Columbus, the chap who discovered America. This conspiracy theory had been created by an Italian author whose book was later translated into Polish and gained quite a lot of publicity in Poland.
1b. Some time ago I read that the mother of Władysław Łokietek, the king who re-created the Kingdom of Poland in 1320, was likely to have been the daughter of Bulgaria's tsar Simeon. Anyway, she was certainly a Bulgarian princes.
2. Bulgaria was the main summer southern destination for Polish tourists in the communist times. People often went there in a Polski Fiat 126p car ('Maluch") loaded with all the necessary things of four persons spending a two week holiday which from today's perspective seems to be utterly crazy and out of this world. I myself have never been to Bulgaria, but my wife was and she says she couldn't buy anything (mostly some water to drink) in shops at the seaside as the response she got was always 'odpochivka'. Even if this was back in the communist times, she swore she would never set foot in Bulgaria again. Despite that, Bulgaria had on avarage a very good opinion among Poles travelling there in summer.
3, A few years ago, a friend of ours was buying summer appartments at the Bulgarian coast at competitive prices and she has been renting them to this very day to fellow Poles wishing to spend a holiday there.
4. Bulgaria along with Romania has in Poland the reputation of a country where corruption flourishes these days. That, of course, doesn't mean that Poland is a country free of corruption.