Is there an easy way to detect methanol in spirits (which may have been adulterated)? Is there an easy way to detect methanol in spirits, which, you suspect, may have been adulterated?
Well that depens on your possibilities.

a) Destillation / Boiling Point (easy, unsafe)

b) Refractive index (depends on impurities)

c) GC (best, very expensive)

d) 1H NMR