I've noticed that one of the Cola Factory servers is hosting a lot of the custom maps, but they didn't bother with fixing any issues before making them available for public.
If someone wants custom maps on his server, he should make sure they work before making them available.
In most cases it's just missing textures and props, which could be added to the bsp or delivered seperate with .res files.
I'd prefer the first method, since it keeps the number of download files at a minimum and won't cause conflicts with other mod files.
The downside is that it changes the CRC of the file and if a client allready has the map in it's old and broken state in his maps folder, he'll get a CRC Error.
So if a lot of ppl allready have the map, it's enforcing the second method of delivering each texture, material and the model files (which consist of several files themself) with their own download.
I won't start to argue about the downside of this, since most of you allready know about the : one big file vs. dozends of small files topic.
Just one specific issue i'd like to point out:
if a material is still used in 5.0 but with a different texture and/or parameters, the only way to ensure the original pre-5.0 version of it is to include the file into the bsp.
Example: some of the materials in ge_citadel_luch are rendered as white wireframe in 5.0 because even the shader changed from LightmappedGeneric (lightmapped material applied to brushes) to VertexLitGeneric (only used on models, has no lightmap).
Including the old material and texture into the bsp would solve this issue because included files will be prefered over external files.
At the current state of distribution, this is still very possible, but if a map has spread out in the community even though it's broken, a serious ammount of ppl would get a CRC error/map differes from the server and i think the majority won't know how to fix this.
Since 5.0 is a fresh start on the custom maps front, i'd like to suggest to make custom maps available only if they are free from issues.