A broken clock is right twice per day. If value theory is incidentally correct, it doesn't make folk theories valuable on the margins - unless of course, if people who hold folk theories do consistently better than rationalists, but then I'd question the rationalist label.
All people hold folk theories. The question is whether, given the set of folk theories you unknowingly hold, correcting an interacting folk theory to a scientifically sound one will improve or degrade your overall performance.
Here's an interesting but very old paper - two theories of Heat Control.
It discusses mental models of home heating systems (thermostats) non-experts use.
These models tend to be extremely wrong from theoretical perspective, but surprisingly useful in practice.
The findings are applicable to a much wider range of subjects than just thermostats, and have certain epistemological significance, especially with regard to compartmentalization.