When uploading Custom Skin texture packs, you agree to a few rules:
You agree to allow Mastermine to distribute your images, publicly. Even skins which are not visible in public discovery (Most Recent, etc.) can be accessed with the right link/id. You understand that your images should be considered completely public, and you are happy with distributing them.
You agree that you have the rights to any images you upload. Images of copyrighted works (art that doesn't belong to you) - are uploaded at your own risk, with your confidence that your skin falls under 'fair use'. If you find a Custom Skin which you believe contains your copyrighted material and would like it removed, contact me.
You agree to mark NSFW skins hidden from public discovery. If you upload a skin that contains non-family-friendly/non-work-safe material, please mark it as hidden from public discovery. You can still distribute the skin to friends using its link/id, but this prevents it from showing up in the Most Recent & Most Downloaded sections.
The above is not legal advice. Have an issue with these rules or the content of a certain skin? Contact me.