However, drugs sometimes falsely represented by sellers as LSD in the 1970s were actually PCP, amphetamine, or other drugs that have quite different, and often unfavorable, effects from LSD, causing unwitting users to incorrectly attribute a "bad trip" to LSD. There are now many research chemicals (DOB 2C-I, DOC, DOI, etc.) that can be nearly indistinguishable from real LSD before use, and thus can be easily confused with "bad acid." Some of these, such as 25I-NBOMe are even potent enough for psychoactive doses to fit on blotter paper, and may occasionally be sold as LSD when the latter is scarce. The idea of "adulterating" blotter LSD with these chemicals, however, has no known basis in fact.