No more than your other user-folders. The
Roaming folder is copied to the server when you log off of a networked computer, but otherwise its used the same as your other user-folders (ie
AppData\Local). As such, the folder itself won’t usually contain files, but rather program-specific folders that contain files (again, usually). If you get an infection that can infect your local folder, then it can also infect your roaming folder and vice versa, depending on what it was programmed to do. Granted, some worms may specifically target the roaming folder to hitch a ride to the server, but once there, unless they are designed to specifically take advantage of a vulnerability on that server, they aren’t any really better off since permissions prevent it from accessing other files or other user’s files from accessing it.
Do you want specific statistics and numbers on the ratio of malware that targets the roaming folder? I don’t recall ever having seen such a figure specifically published, but it should be simple enough to scour any given malware-database (or other sites that analyse changes made by a file), searching for the strings
AppData\Roaming to find ones that made changes to that folder.