Sadam virus was particularly unusual in that prior to KS2 where the disk i validator was included into the ROM it was possible to be infected by simply inserting a disk infected by saddam virus You didn't even have to boot it or even access any files.
Boot block viri were common in the early days. I never got infected by any of those and virus checkers could easily detect and repair (assuming the disk did not have a custom bootblock). I remember using some program or another to keep a database of custom bootblocks for quite a while in my early days of Amiga. I never actually needed to use it to restore though.
Viri attaching themselves to files came later (probably as hard drives became more prevalent). I ran VirusZ in order to protect myself from this. I think a lot of it was media hype. I mean clearly there were a lot of viri out there but I dont think they were nearly as common as some people were claiming.
I'd say the Happy New Year HNY virus was probably one of the most common link type viri
https://www.vht-dk.dk/amiga/desc/txt/hny-9697.htm