Uh oh not this thread again
LSD will always be LSD, that much has already been stated (so I won't beat the living shit out of
that dead horse like I usually do...). My belief on the matter is pretty much as jammin83 and Peacephrog1972 eluded to - impurities in the final product through imperfect synthesis. This is only part of the 'answer' though, as we all know how strongly set/setting/etc etc etc can vary a trip.
I'm not a chemist by a LONG shot, though my understanding of the
actual "LSD analogues" like 1P-LSD, AL-LAD, ETH-LAD etc are that they're as jammin83 states - a step (or more) beyond the LSD stage of synthesis. But that's somewhat pointless to discuss any further, as it may start to tread the line of synth discussion aka against the rules