I either write out the description, draw my own picture, or both (usually both). It is a Personal Choice not to use any art that wasn't either 1. made by me or 2. made for me (by gift or commission).
It's one part because I can and one part thats how it Was in my first rp group. You either made/obtained your own art, used a doll maker (remember when those were popular for ocs? haha), or wrote it out. You weren't allowed to use anything you didn't have explicit permission from the artist to use, and I've just always carried that with me.
I've been unable to app to some rps because of it, yeah, but it just feels Weird to use other people's art now (especially now that I am older and actually like in art school and people have payed me to draw their characters) and it kind of became my own personal Code so That's That.
I'd say as a side effect that made me a real stickler for sourced art (that includes photography people! Even if its a show screenshot say what show!) but I think being an artist I'd still be a stickler even if I did use other people's works for a face claim. It's kind of awkward and uncool to see a personal piece being used or, god forbid, someone using one of YOUR ocs as theirs without your permission. Not to mention it also gets weird with commissioned pieces sometimes the client doesnt want that going around and when it comes to Japanese artists on pixiv there are rules about copyright and reposting (which is why when an artist gets their art plastered everywhere without their permission they either vanish or change names).
That being said I have no issue if you use drawn art or photography, as long as you source it ;3
Though I do admit that sometimes I find using photography weird because, like, sometimes ppl just use celebrities or like random selfies off of facebook and that seems... Weird... I'm not sure if I would be freaked out or flattered if someone used one of my selfies as a face claim... huu...
AND as a side note to the people making a stink about not having the money to commission: Ask the artist if they do trades and they if would be willing to trade art for writing. It's not something people think about often, so most artists won't consider it unless you ask. Sure you may still get turned down (some folks don't accept trades at all) but it's one more option to you. Sometimes artists also do raffles or give-aways, especially if you follow them on twitter/deviantart/tumblr. So don't just look at an artist's page once and then forget about it if you can't pay them, you may miss out on a perfect opportunity to get some free art of your character. (That being said DON'T try to make friends with someone and expect to get free art, that's just rude and manipulative)