I found a great guide off Reddit to follow if you want to know if the acid you ate was real. It comes from WishIlivedintheNL.
Hi everyone, I've been stocking up for festival season and I've started to notice the usual large quantities of bunk/fake LSD. I've been at the game for a while and figured I could put together a kind of checklist for identifying if what you really bought is LSD!
Before I start all of this I'm gonna talk a little about test kits and LSD. There are two kits that can help you determine if you have LSD. The Marquis and Erlich reagent (THE erlich reagent is the commercially available LSD tester from Bunk police, easytest, NicU, etc.). I've never really used a marquis on LSD, I think you're pushing your luck. With regards to the Erlich I really do not trust it. I know that it triggers in the presence of an indole, and when you look at the chart it's clear LSD is the only drug that can fit on blotter; However, I've spoken with many people in the RC scene and it is very common for people to dilute their bunk drugs with a very easy to purchase indole. That means, that if someone is laying a sheet of bunk L all they have to do is grind up some melatonin and put it in their solution. If they do that their shit will trigger an Erlich test.
Step 1: Trust your source
This is kind of a bullshit one but from my experience you need to trust your guy. Always ask if he's taken some of the drugs he's about to sell you. If he has you need to ask him the following (this is why you need to trust he isn't bullshitting you on his response)
How long did the trip last (it should be between 10-14 hours)
Did you mouth feel numb when you took it. Real LSD should not numb your tongue at all! A few times I've had some it has numbed it a little but if you can't feel your tongue you've got bunk shit. (If anyone says they could "taste the acid" it was probably bunk as fuck)
How did you take the tab/dose? (If your guy says you HAVE to keep it in your mouth to trip then it's not L, I'll talk more about this later)
How many did you take? (FROM MY EXPERIENCE most LSD is layed/dosed out at around 50-60 micrograms, at that dosage your trip normally is)
1 dose-you feel a little funny and can drink/smoke as much as you want
2 dose-colors are vivid, things look closer or further than normal, some tracers
3 dose-Things look funny, mild pattern shifting, definitely know you're tripping hard.
If any of the questions to your dealer seem a little off or he responds with any of the negative responses I've listed above then you should tread carefully and maybe only buy a few hits to try it out first.