I must say that the rainbows and tiedyes I've seen in the last two years are not LSD. They are confirmed DOI. They taste nasty and have a three hour come up. Beyond not being a typical LSD dosage response curve or LSD trip in general they were recently confirmed as DOI by a chemist that was laying sheets that looked like this:
http://www.erowid.org/chemicals/show_image.php?i=lsd/lsd_blotter_ap_kaleidoscope-2000.jpg
I posted this earlier, but seeing Cecuk's post made me post it again. I ate 4 (maybe 4 1/2) of these May 2006 and was spun for over 24 hours. I feel way more fractured off DOI than I do off what I've assumed to be LSD in the past. It's fun, but it's not the same level of beauty and it comes with more side-effects. What feels like an afterglow with DOI is just the tail end of the trip.