The Trashman stuff is done in a much cruder style than his later stuff. I think a lot of the underground artists in the '60s looked down their nose at Spain a bit as he wasn't really into faddish lifestyle flourishes, and wrote very much from a working class Marxist perspective, rather than from a posturing middle class bohemian perspective. You don't get the impression from Trashman that he was at all impressed by some elements of the underground lifestyle himself, either.
Apart from Trashman, the other thing of his I really enjoyed was his comics adaption of Gresham's Nightmare Alley, which is magnificent.
(dogpoet, not BHG)