Listen to this. I've written some down manually yes, but not in plain text either. I've got my own little algorithm which I use to make it look like a ordinary work document which wouldn't interest others at first glance. This is combined with other work documents so it gives it a little more camouflage.
Printing is a flaw in terms of security & that's why I've personally never dealt with a paper wallet unless written down manually myself. Honestly, It's much better to just write it down manually & make sure it's 100% correct with capitals etc. Although I must say the odds of someone 'intercepting' or looking at recently printed documents is very low.
Trying to mask it as a ordinary document will be a good idea to further mask it, but if people are going to go this far to try get your coins they'll likely have a bot that looks for your keys. I'd be very scared of making a mistake righting them down by hand.