just because it's a psychedelic doesn't mean it's real acid. there are lots of drugs that will fit on a blotter and make you trip balls.
lsd is generally accepted as being tasteless at doses that fit on blotters.
the old standby for fake blotters used to be drugs like DOB, DOC, DOI because they could fit on a blotter. but those took a good 2 hours or more to come up and generally are considered too rough and long lasting to be mistaken for cid.
the 25x-NBOMe compounds which have greatly risen in popularity (because they are potent hallucinogens that fit on a blotter) are, however, pretty nasty tasting. but their effects are very similar to LSD, especially if you're expecting it to be acid. since the 25x compounds are much cheaper and easier to make than LSD they have enjoyed a rapid rise in popularity.
the only way you can tell with absolute certainty is by testing the blotters chemically. you can't tell for certain by dosing them.