1) I look for the mainstays, including the main cichlids such as: Oscars, Severums, Angels, Firemouths, Acara's etc, then bonus points for the more niche fish such as jaguars, Salvini's etc. Then I like to see the popular tetra's such as neons, cardinals, black neons, as well as other popular varieties, again bonus points for rarity. Then on and so forth from other genus', conversely, if the shop has minimum space, I'd like to see the stock chosen wisely.
Also, every aquarium must look pristeen, no green hair algae on the substrate etc; indeed if there is substrate, bonus points for looking maintained.
All fish should look healthy, if not should be shown to be getting treated or segregated from other fish.
Should hopefully stock a good variety of decorative items including driftwood, manzanita, as well as functional aquarium necessities such as filters.
Hopefully also see a well maintained selection of plants.
2) I like Jaeger heaters, but I agree with
Fat Homer
on the Ferplast.
3) basically included in point 1 lol