Can a lot of viruses infect the recovery partition so that windows can't re restored safely?

Definitely YES.

If you follow the repair procedures for most viruses, from about any anti-virus vendor, they will tell you to disable Windows System Restore. When you disable Windows System Restore, all restore information is deleted, including any viruses.

This is because computer viruses, Spy-ware, trojans, etc. can lurk in the System Restore locations. You wouldn't want to ever restore these infected files.