Well sometimes you can get a rough idea from graphs as regards how the tint will look, but there’s still some guess work involved because of the binning process. You could have an LED get top marks in a test from a forum member, but it could turn out much worse if you get it in a light, especially if you don’t know every detail about which bin a certain manufacturer got.
I’ve got LED’s on their own before but I have to put them in something to get an idea of what they’re like. You could always ask some more experienced members about a particular LED and where they got it from, that’s helped me in the past. Convoy lights can be one of the cheapest ways to try out certain emitters, especially in smaller and cheaper lights like the T2, T3 and S2+. Often times I’ll just wing it and see if I like it.
I’m not aware of there being any particular way of testing emitters on the cheap besides buying lights that have them installed already, besides bench testing them with fancy graphs and spectrometers etc. I tend to wait a while before jumping on the hype train for a particular emitter so I can tell what the general impressions are of it, which ones to avoid, where to buy from etc. If you ask around on here on or on the r/flashlight Reddit page you’ll get some idea of what’s good and what isn’t.
Edit: I’ve learnt to read some basic info from LED datasheets like where a particular tint bin is on the ol’ BBL chart etc, that’s been very handy in the past