In the western (not in the sense of the old FRG, but Benelux-adjacent) federal states, I have not yet seen any Poles in jogging pants on construction sites. Polish craftsmen residing in NRW/RLP/HES are mostly exemplary, precise workers (and leave clean construction sites).
In the northernmost federal state, that does happen occasionally. And the construction site was not clean either. But I do NOT want to attribute that to the employees' origin. What I wanted to say is: professionals should do the installations, not amateur helpers, even if it costs a few marks more.