You're Doing Tieflings Wrong

Tieflings do not have a standard skin tone, and 3e did not assign them standard physical features.

Look up Tieflings online in the D&D 3.5e SRD. "Many tieflings are indistinguishable from humans. Others have small horns, pointed teeth, red eyes, a whiff of brimstone about them, or even cloven feet. No two tieflings are the same." Note the use of the word or in the list of physical features, not and. And definitely note that the description reads "many tieflings are indistinguishable from humans". This is the full physical description and does not address skin color. This passage comes from the monster manual (where tieflings used to be) and the physical book provides an illustration of a woman who looks like an ordinary human.

For reference, even the description of tieflings in 2014 5e PHB, under the subheading "Infernal Bloodline" reads "Their skin tones cover the full range of human coloration, but also include shades of red." The red skin thing is new in 5e (or maybe it was 4e?) and it suits cambian demons, which are creatures with a human parent and an infernal parent like Hellboy.

In 3.5e, Tieflings are categorized with Aasimar under Planetouched in the Monster Manual. Quote: "Planetouched is a general word to describe someone who can trace his or her bloodline back to an outsider, usually a fiend or celestial." To reiterate, if you're a tiefling, you have a fiendish ancestor. That's bad. Here's why. Tiefling alignment is given as "usually evil (any)". The alignment of usually evil is the basis for discrimination against tiefliings. To quote 3e's definition of evil: ""Evil" implies hurting, oppressing, and killing others. Some evil creatures simply have no compassion for others and kill without qualms if doing so is convenient. Others actively pursue evil, killing for sport or out of duty to some evil deity or master." THIS is this the bases for discrimination against tieflings. Evil alignment in 3e is traditional black-and-white-morality, objectively bad.