Learn Polish: Zobacz, jak te fachowce spartaczyły gniazdko! - Look how those professionals botched the socket!

This is the depreciative plural, which is the main focus of this lesson. Fachowiec (professional or tradesman) is a masculine personal noun, so standard grammar requires ci fachowcy. However, by intentionally using the non-masculine-personal demonstrative te and the noun ending -e, the speaker expresses strong contempt or frustration at their bad work.

Since the tradesmen are men, why does the verb end in -yły (spartaczyły) instead of -yli?

When you downgrade a masculine personal noun into a depreciative form like te fachowce, the grammar of the whole clause must follow suit. The subject is now treated grammatically as non-masculine-personal, so the verb must take the non-masculine-personal past tense ending -yły rather than the standard masculine-personal -yli (spartaczyli).

What kind of word is spartaczyć?

Spartaczyć is a very useful colloquial perfective verb meaning to botch, bungle, or do a terrible job on something. It comes from the old noun partacz, which historically meant a bungler or an unskilled craftsman who did not belong to a professional guild.

Why use the diminutive gniazdko instead of just gniazdo?