If its bitter its a spitter right?!?! Have you ever had extrelmly bitter white on white that was legit L? Because If this stuff isn't legit its a close realitve of Lucy.
Probably DOC or DOM. They're very acid like but last significantly longer and have a 2-2:30 hr come-up. They're a lot cleaner and more visual than DOB which is said to be a terrible 24+ hour trip, and the worst of the DOx compounds. If it's bitter it doesn't mean it's always bad, but it's most likely not lucy.
If you come up in 30-45 min and have 8 hour trip it's probably lucy but not clean of other by products which can be bitter.
Most LSD blotters I've had were bitter to a degree, but there's a difference between a bitter LSD blotter and a DOx blotter; the latter is furiously bitter. Obviously this difference is impossible to communicate unless you've had both . . . DOx blotter literally tastes like a little drop of mdma or codeine in your mouth. lucy can take 2 hours to come up as well . . . the big give away will be the effects (I still don't understand how people confuse a DOx trip with an LSD trip, they have completely different body effects and head spaces, it would be like confusing an MDA trip with an LSD trip . . .) and the duration, with DOX you are just getting into the thick of it at the 8 hour mark.