Producer Brian Deck demonstrates three SM57 placements on a guitar speaker cone, each results in a noticeably different tone. Every position gets an audio playback so the differences are immediate and clear.
On-axis at the cone center gives you the most aggressive, attack-heavy sound. Moving the mic toward the edge of the cone, same distance but still pointing straight in, softens that attack and smooths out the transients.
Pointing the mic at the center but at an angle is the third option. Instead of the sound wave hitting the diaphragm head-on, it glances off, which produces the most controlled and rounded result of the three. That single variable, angle versus on-axis, is worth understanding as two options you can use when shaping a guitar tone.