Are all the polish big cities like this?
Pretty much yeah. European people have a long tradition of mimicking behavior from the US without understanding the cultural roots of what they're doing. So graffiti caught on big time (it was big in Germany before reaching Poland) and most of the little hoodlums responsible have no idea what they doing.
Basically spray paint graffiti comes in three varieties:
1. territorial marking of the kind that dogs and cats do, figuratively pissing to warn enemy packs away
2. a desire to make the urban environment as ugly and dysfunctional as possible (so that those with no interest in social order or progress can act unimpeded by social pressure)
3. symbolic stealing of property (you thought it was yours but any young thug with a spray can do what they want with it).
Graffiti has always been with us but I hate and despise the spray can kind as a direct assault on the social contract that makes cities liveable.