It's extremely hard to save a seat especially if you live in a highly-populated metropolitan area where people are constantly on the move and might not have the manners you'd expect from the average adult so, sometimes you might need to take things into your own hands. And no, we don't mean boxing every guy who happens to take your seat on public transportation or making threats to some lady who took your seat at a local park bench but a little trickery can possibly keep patrons from taking your seat.
These spill illusion seat savers can guarantee you a seat unless, of course, you're dealing with a neat freak with OCD that can't stand to see spilled ice cream, spoons, or coffee cups in seating areas. There's nothing wrong with a little deception every once in awhile especially for the sake of your own comfort.