Executing unverified script files or downloading "executors" from sketchy sites can infect your device with viruses or keyloggers designed to steal your passwords.
Game developers frequently update their systems to patch exploits, rendering older scripts broken or instantly detectable.
To mitigate risk to your main profile, script testers frequently resort to using throwaway alternate accounts. ABA Script - Pastebin.com
Platforms like ScriptBlox and Rscripts host community-submitted code for various games.