download game mod & trojan, virus ???

one of my favorite games is the Command & Conquer Universe--

I have bought most of the versions---
(can't wait for next years new release)
(even though C&C 4 sucked)

my question is---
how safe is it to down load free game mods???
has any ever been infected with a virus or trojan????

for C&C Zero Hour there seems to be several game faction mods plus map packs---

I have always stayed away from free wallpaper & 3D Themes to stay away from all the adware & malware--
spybot goes nuts after downloading these type files--

would I run into problems downloading the game mods????
virus , trojans????