well you can sometimes get pulsing effects, but without any control over any depth or rate. You'd do a lot better to build an LFO of some kind.
I'd say capacitors are probably the least useful common component if you're using random bending techniques. They are a lot more usable once you learn some electronics theory.
Rather than worrying about capacitors holding a charge, as suggesting on that link, i'd be a little more concerned about connecting a cap backwards across a voltage and it blowing up in your face!