We have a long time running lfs here in Des Moines, Aqualand Plus, I've frequented now and again. They have a lot of larger oscars often in shoddy shape and on reading the oscar info offered on their website I can see why...
www.aqualandpetsplus.com/Cichlid,%20Oscar.htm
They're still claiming medications they sell will fix HITH and also HITH isn't a real concern for oscars, that oscars can be kept in 30 gallon tanks and two can be kept in 55 gallon, as well as a few other aweful bits of advice.
I still might get some supplies there if the price is right but I don't think I'll be attending to anymore of their advice nor likely getting any livestock there.