In which case I'd suggest that this implies that the problem was much earlier in the process chain than the scanning stage.
If you have crappy source material (either shot poorly or stored poorly), then obviously an expensive scanner is not going to help. Just like how an expensive sound system is not going to improve the sound of a scratched up 1980s audio tape.
On the other hand, as a fair number of my shots were taken tripod mounted, with prime lenses, on ISO 50 film, and I have several thousand photos to process, a cheap and manual scanner isn't really going to cut the mustard.
Lastly, "vast sums of dosh" is a relative term here. The scanners that I am talking about are only expensive compared to the toy scanners. They are vastly cheaper than professional level scanners, which start at 15K USD for an entry level Hassleblad, and then to multiples of that for real drum scanners. The scanners I refer to in my earlier posts cost less than a good amateur DSLR body.