You need to get a reagent to be sure, like Sekio suggested.
Taste is subjective and hard to compare. While LSD is indeed tasteless at typical doses (although bitter at somewhat higher doses apparently), impurities could have taste. I don't think it is just the ink, I have had LSD that tasted like soap a few times (all roughly in the same period). Though it is possible the ink tasted like soap, I got that taste with different types of blotter.
So we cannot differentiate between potent psychedelics only based on taste, blotter design, the way it makes you draw or what it feels like to you. Even if people can list a lot of differences between psychedelics that fit on blotter, there are also a lot of similarities.
Speculation is not really what we like to do here, it never really leads anywhere anyway... and it can potentially result in misinformation.