One of the oddest through trains in Scotland must be the hourly xx:22 Cumbernauld to Dalmuir run, which goes through Coatbridge, Motherwell, Hamilton and Glasgow Central. It does serve a useful function, linking communities in Lanarkshire. But it is a train that no sane person would ride end to end (and not only because one end is Cumbernauld!).
The xx:22 from Cumbernauld gets to Central one hour later. You're better off getting the xx:29 to Queen Street (arrives in the low level at yy:04), or indeed the xx:40 (arriving into the High Level at yy:09) and walking. In terms of people traveling to the West of Glasgow, again the later trains get you there earlier. Same is true from Greenfaulds. It then passes through Coatbridge Central at xx:31, where this service to Glasgow Central (still some 51 minutes away) is eclipsed by the much faster journeys on offer from the nearby Sunnyside to GLQ LL (express trains taking less than 15 minutes). Then it goes to Whifflet at xx:33, where you can yet again change and catch a quicker train to Glasgow Central Low Level. Even at Motherwell, you can change onto a direct train to GLC HL and beat the train that you're on. It's only once you get to Airbles that the train starts to become useful for journeys towards its terminus at Dalmuir.
Of course, this service is exceptionally useful for travel in and around Lanarkshire, which is the reason that runs. But it certainly fits the category of "ridiculous through trains", where Glasgow passengers will find that changing at any of the first five stations will get you to your destination considerably quicker, via no fewer than five different routes.