Although I never used an "imagization" tool (for example, Docker) I understand a container as an instantiated (running or stopped) image which in plural are simply put, a server environment and corresponding application/s, cloned from one computerized machine into another computerized machine (likely a virtual machine);
I further understand such cloning operations save time because application/s (and maybe also an OS) shouldn't be installed again and configured again to reach the state of the cloned machine, so one could start from that state and make changes from there.

My problem

When I still used Facebook, I spoke there with some anonymous sysadmin who claimed something like he doesn't use imagization tools as an image could be contaminated somewhere along the process with malicious software without him knowing it.

I am not sure I enough understand what "imagization" tools do and the subsequent opinion I presented.

My question

Are there arguments against using “imagization" tools in the literature and if so, what are the main ones?