delphiandomine, there is a big difference between what is written on some website, and real life.
Obviously, I don't suppose you actually have any money to put into a bank account. Spamming Polishforums constantly obviously isn't very lucrative. How's the Adwords ban affecting you?
I can assure anyone on this forum that mbank is more than happy to open accounts for foreigners - the only condition is that you need to have an address in Poland that you can use, though you don't have to be registered there.
That's what the UK Foreign Office is saying in its advice to travellers to PL. They also mention VISA, but my friend from Scotland who was here last week couldn't use her Maestro card. Luckily she'd brought a credit card too. The FO says that banks are working on the problem.
I doubt they'll fix it anytime soon - they've had what, 3-4 years to fix it and it's still a problem? Then again, even in the UK, Maestro/Switch acceptance has always been rubbish. Probably the best advice is simply to steer clear of Maestro full stop!
Visa is safe though, as far as I understand it - the only thing is that people should be aware that Visa Electron isn't accepted everywhere. To be fair, I have a Visa Electron card in Poland through mBank and have never had problems with it being accepted here - though I *think* PKP Intercity won't accept it for tickets onboard.
The best idea is as you say - always take a backup credit card.