I always kind of thought that if the thought of LSD scared me then DMT would absolutely terrify me. Although the shorter duration would mean that if it went badly then at least it would be over sooner.
I remember reading about the former 6 time Mr. Olympia Dorian Yates who went to the Brazilian rainforest to take ayauaska (sp?) but I don't think it was his first phychadelic experience.... Now that DID sound scary but he said he was puking and shitting himself due to having to drink litres of foul liquid. He said he tried it again in the UK by smoking DMT powder and that was a far more pleasant experience. The whole puking and shitting thing was I imagine a bit off putting