When the series was originally being promoted, 'suits' at NBC thought the character looked too 'Satanic', and early posters and promotional materials show Spock's ears and eyebrows airbrushed to human roundness.
The satanic figures of demons are often shown to be far from their angelic roots, though occasionally more tempting demons are shown as a female succubus; a provocative woman who seduces men.
Not everyone has heard the true story behind the inverted cross, so many people believe it's a symbol of the Satanic church which appropriated it for their own use.
Artwork in the press-packages showed Mr. Spock with ears airbrushed to roundness - the pointed ears, they thought, might be considered 'satanic'.
Contrast this with what most people consider as mainstream rock music, particularly those with Satanic or anti-establishment sentiments.