I guess the first thing to look for in order to spot a fake is the packaging.
Walk away if the shopkeeper says "sir je ye original hai humne apni packing me dala hai OR hamara maal loto me ata hai original packing ni ati."
Then inspect the shock. It should have the name of the company embossed in metal with serial number. Not some chingpong sticker on it.
Last. Buy from a reputable shop.
I spotted fake locally painted and repaired shocks packed in Honda boxes claiming made in thailand. When I inquired where is the company name embossed?
I got the funniest reply from the shopkeeper. "Sirje hamara maal loto me ata hai to scracthes par jatay hen hum yahan paint se touching krte hen" lolz
I wanted to take a picture of it but he was not comfortable with it.