Spelling it cum makes sense (sorta). Spelling it come makes you look like you are unaware of the differences between semen and the act of arriving someplace.
All kidding aside, I understand that come has tradition behind it and cum is an interloper, but I’m rather enamored of separating the two concepts via spelling.
I think “cum” makes the user look like an uneducated hick. I hate that word. It’s just…skeezy, not to mention ignorant. I have reason to use the word a lot in my line of work, and there are some publishers who use “cum” as their house style. I have actually gotten into arguments over the issue, and as a result, the editors no longer go through and meticulously change come to cum. Except for one publisher, but I decided that wasn’t a hill I wanted to die on.
Having said that, if I’m writing something lowclass and skeezy and I want it to feel like something filthy, I’ll intentionally use “cum.”
Well, I think I really object to it because I don’t think they are separate concepts. “Come” in the ejaculatory sense, is clearly a figurative use of the verb “come” - you have come to, or arrived at, the climax, when you come. The noun “come”, meaning the stuff that emerges when you come, is derived from the age-old practice of using verbs as nouns. Like “harvest” (verb) and “harvest” (noun).
Spelling it “cum” is just cutesy and dumb, like writing “luv” instead of “love”.
One of my favorite police reports I ever had was where the cop couldn’t decide which one to use, so he scratched out CUM and wrote COME. He was using it as a noun.
I saw, I conquered, I cummed.
Hmmm, I’ve always gone with come. If I may ask a related question, does anyone know if jouir in french has an associated noun? If someone jouits is there jouisse all over the place? Anyone know?
In fact, there are equivalents in other languages - amusingly, in Japanese one “goes” instead of “comes”.
Orgasm or semen.
“Come,” when I use it at all. I hate the world “cum.” It just looks hopelessly stupid and illiterate.
if I want to be low class then cum is the word, if I am writing in a staid style then ejaculate or semen would be the way to go.
I don’t use the word at all (with either spelling) unless I want to look like a subliterate moron. I hate it. Semen, ejaculate, jizz - please, use anything else.
This is no moment to be discussing semantics!
Verbally, it’s “come”/“came” (I think “cum” is hopelessly uncouth and refuse to even think of it being spelled that way), but for written purposes, the verb is “climax” or “ejaculate,” with the noun usually being “semen”.
Cum looks dum.
Wait–“come” is subliterate, but “jizz” is okay? 
Jizz is how classy, intelligent people say they are ejaculating on your tits.
Directly? How frightful! Please, put down a doily first!
While I agree with you in principle, the end effect may be something like decoupage if one doesn’t act quickly in removing said doily after the fact. I’m not sure if that’s better or worse.