How can you determine a busted capacitor?

There have been a few errors in recent years with capacitors that go bust from normal use. These are most often leaking electrolytic fluid from a crack at the top or the bottom. This fluid is most often drying up and leaves a dark brownish crystalline compound on and around capacitor.

Some other capacitors are just bulging upwards on top and give no signs apart from this.

A healthy capacitor has got no visual deformities.

If in doubt about a certain capacitor then de-solder it and test it in a multimeter that can measure its capacitance.