I never trusted these cheep alligator clip wires very much since they always use very thin wire, but i have never seen one with fake copper coated steel wire.
I often swap out the wires on these clips with something thicker, and solder it properly. The original ones wires are usually just crimped into the crocodile clip with the insulation included. This works for some time but then develops a intermitent bad connection, as a result causing me lots of frustration when things mysteriously stopped working at random times. It also pulls out if you jank the wire too hard. But the crocodiles tend to be just fine, so all it needs is a new wire and proper soldering to hold it on.
Oh and copper wires also become 'magnetic' once you pass enough current trough it. Above about 100 or 200 Amps of DC you get magnets sticking to the wire like its made out of steel. This is why it is important to tie down wires carrying large pulse currents as the wires will try to 'run away' due to there own magnetic field.