Problem is if they're too subtle then the character isn't gay.
Every time a "what do you want to see in Trek" topic comes up, it turns into this.
If "too subtle" means a character isn't gay, then where is the dividing line? Should they wear a sign around their necks, or make out in the ship's corridors like high school kids between classes? I'm being obviously ridiculous, and I like it.
In my everyday travels through life, I'm sure that I meet gay people all the time. I don't know who is and who isn't, and I don't care. A person's sexuality is not the reason that I interact with them.
Do what you want, be who you are, and don't inflict yourself on people who aren't interested. That's a pretty good way to live, in my opinion.
The real question is, does a character's sexuality add to or detract from the story?
Star Trek isn't about who likes who, or which thingy goes where. It's about Kirk and Spock and the Enterprise and space and what's out there and having some fun adventures.
All that other stuff is boring.