Morphine
Experienced
The ear you need to adjust the patch is the same level as one that is needed to build your own . The main issue is if patches aren't built on a true flat response system with a control they will not ever sound right on anyone else's rig (ie the same). Until there is a reference or control method that can be applied to all systems to tune the global eq to flat (in your environment .) Buying patches is pointless or at best a lottery . Hence the need for free samples .
Adjusting a preset and building one completely from the ground up are vastly different.
Anyone who is that sensitive to potential differences in what is heard from a sound sample vs. what is heard on their system will likely never be 100% happy with presets created by other people. Heck, if they're even looking at user created presets then they're not 100% happy with their own either. A free sample also isn't going to cover the range of what you're getting when you purchase a pack that contains, in some cases, dozens of presets.
I'd argue that user created packs simply aren't for you. And that's perfectly okay. Nobody is forcing you to take a gamble and buy them. I also don't think any of the guys in the community offering them make their living doing so. So there's no real reason to give away their work in the hopes that it will generate more sales (funny business model, really). There's audio/video samples provided. If you like what you hear and can accept that there's going to be some level of variance, cool. Buy it. If that's not a gamble you're willing to take, don't.