You cannot open .mesh files with Notepad but you can open the .xml file with it (if you're using Blender).
When using Blender you export the custom made object as a .xml file. While still in that format it can be opened with Notepad which give all the coordinates and lots of other scripting that make up the object. It is quite a lot of text though so it wouldn't be possible to copy and paste all that information in a post due to the limited amount of characters in a forum post. Though if you could, members would only have to download the .xml converter and convert the .xml to .mesh themselves.
So no, you can't use your idea on a .mesh file but you could on a .xml file though only if the creator of the .mesh uses Blender. Not sure if .xml works with other 3D modelling programs.
I wouldn't worry about corrupted .mesh files. Like Thierry mentioned, files that require an administrators permission such as .exe files are usually the ones carrying any viruses.
Mmm... I see xD.
(I don't want to get off topic, but could you recommend some maps to me? xD)
I was just asking, though, what if that feature 'was' added?
You will find a large variety of maps
here, you may want to look around that board until you find something you like.
I hope you find this information helpful