Editing here because based on some replies my message wasn't clear: I was talking about expertise in plumbing exhibited by one of the protagonists, not someone watching the movie obviously.
That's the point, expertise in an area can completely distract from the plot entirely. I can't even watch anything medical-related with my wife since she'll get annoyed about inaccuracies and start complaining about them. Doesn't matter how unrelated to the actual plot it is.
The Plumber (1979)
A young couple, living in a campus apartment complex, are repeatedly harassed by an eccentric plumber, who subjects them to a series of bizarre mind games while making unnecessary repairs to their bathroom.
Of course in a lot of cases expertise is needed. However that isn't important. The important part is you have more knowledge about something than the average person.
> Simon Orrell: My first exposure to “The Plumber Problem” was sitting in a theatre with my dad in 1973 watching “Emperor of the North” and my dad leans over to whisper, “They didn’t make culvert pipe like that back in the ’30s. It was plate, not corrugated.”