I would guess there are teachers doing very well in Warsaw, but there are bound to be others not doing so well as expected
This much is true.
I'm thinking about the ones who come on here, with a 4 week course behind them, asking about extra work and charging low fees. Don't you think when their money runs out, they would be desperate enough to to do any job to stop themselves from starving?
I worked in ELT (mostly in management though I did always also do lessons) for 10 years and never came across anyone washing cars etc. Even the scummiest nomarks (I chose those words carefully) can usually get enough work to survive and in any case there's too much competition amongst unemployed locals for a foreign teacher to pick up work in a car wash.
Warsaw is a big city, do you really know everyone who calls themselves an English teacher there?
The troll who started the thread seems to know about "most" of them:
Oh is it true that most English teachers now wash cars to substitute there income?