Honestly anything can be faked bro. Amps are harder to fake because supposedly more expensive since it's more than just slapping a label on an empty vial from a lot of places legally. I've never seen amps readily available.
I would more worry about the drug being faked rather than the brand. Test, dbol, decca, anadrol, winnyand tbol come to mind as being less faked in my opinion since I cant ever remember getting those as fakes. Underdosed, maybe. Primo, anavar, masteron, tren, really come to mind of hearing people getting fakes. Either it's just oil or another drug; anavar ending up being winny, tren ending up being prop. It's just a gamble unless you have history with a source.