how can I remover these turn offs?
Recrystallization. See Post 408293 (https://www.thevespiary.org/talk/index.php?topic=8385.msg40829300#msg40829300)
(Rhodium: "The Stimulants Forum FAQ", Stimulants)
Is pure amphetamine (or meth) tasteless-odourless?
Odorless they are, but they still taste bitter.