I believe both of these spur routes are unsigned, though I did NOT actually travel the spurs in question. I drove down both MO106 and MO112, looking more for junction signage rather than looking explicitly at my GPS for them. I only realized after getting quite further on down the road that I never saw warning/junction signage for either of these routes. I tried to double check on GMSV...MO112Spr is a bit more conclusive. From
this image at the junction of 112/112Spur, I see no reassurance sign, and actually what is most likely (given the shape of the sign and the pavement markings leaving) a MoDOT MAINTENANCE ENDS sign. Unfortunately, there are no GMSV images at MO106Spur, so I can't prove that it is unsigned, other than along MO106 itself.
So that's the info as I know it. Maybe they should be taken out due to lack of signage, or maybe not yet.
v.