Not that bad, but I remember one encounter with a bit of infrastructure that defied explanation, but eventually some veteran remarked 'oh yeah, we added that during the transition away from microfiche.' Another entire system had been built to create a CD-ROM prodect that they had kludged to pipe into a web application in a way so ugly my eyes can't unsee it.
Thing is, as the owner of the Big Spreadsheet, you figure out how much it will cost to tidy up this shit, and say 'not on my budget, just keep it working.' Yes, I was that guy. Sorry.