You all forgot one test that is affected by high chlorine levels...all DPD chlorine tests (comparator is shades of red/pink) (and to a lesser extent FAS-DPD tests).
They can "bleach out" and remain colorless at high chlorine levels (DPD over 10 ppm FC and FAS-DPD over 25 ppm---but are usable at higher FC levels with certain modifications.)
If your chlorine test is reading low and you suspect there is chlorine in the water (expecially if you saw a pink flash before the DPD test turned clear) do an OTO test (comparator is shades of yellow). It is a foolproof test that will ALWAYS tell you if you have chlorine (or bromine) present.
If it turns yellow to deep yellow it's most likely swimmable, if it's deep yellow to orange you are most likely shocking, if it's orange to brown stay out of the pool but throw in the whites because you have a pool of bleach!