Hi 4rc28, things can get annoying when your map is "stolen" but under certain circumstances there are inocent reasons for some transgressions.
Besides being a possible compliment - as I understand it in the world of mapping and modding, if the MIS file (or project file) is included with the download then PPL may feel they have an inherent right to use it as a basis for a map.
This is generally acceptable as long as they change it sufficiently to make it a different experience, this is also how PPL get feedback and learn to make their own.
Giving credit is usually done if stipulated in the download though you rarely see that.
This implies it's polite to ask but not compulsory. So the problem remains as one of tolerance.
