Oxy-fuel cutting is a chemical reaction between pure oxygen and steel to form iron oxide.
It can be described as rapid, controlled rusting.

Preheat flames are used to heat up the surface of the steel to approximately 1000°C (1800°F - bright red color) but below the metal's melting point. A jet of pure oxygen is then directed toward the heated area in a fine, high pressure stream. A vigorous exothermic chemical reaction takes place between the oxygen and metal forming an aluminium or iron oxide or rust. The pressure of the jet of oxygen blows away the slag or oxide forming a cavity. The preheat and oxygen stream are moved at constant speed to form a continuous cut.

The answer is that it cannot! This depends on the melting point of the individual metal's oxides. Only metals whose oxides have a lower melting point than the base metal itself (low carbon steel and some low alloys) can be cut with this process. Otherwise as soon as the metal oxidizes it terminates the oxidation by forming a protective layer.
In other words Oxyfuel cuts by burning, or oxidizing, the metal it is severing. It is therefore limited to steel and other ferrous metals which support the oxidizing process. Metals like aluminium and stainless steel form an oxide that inhibits further oxidization, making conventional oxyfuel cutting impossible.

It takes some experience to be able to distinguish between a top and an inferior quality cut. Main points to judge from are:

• There must be clean smooth cut surfaces with vertical drag lines
• Little to no dross (slag) on bottom edge (easily removed)
• Cut surface flat from top to bottom without undercut
• Squareness of the top corners, that is the eventual arc must be of a minimum radius
• Cut face square with respect to top surface

The Main Terminology relevant to Oxy-Fuel Cutting is the following:

• Preheat Flame
• Oxygen Stream
• Torch and Cutting Nozzle
• Cutting Speed
• Material Being Cut

The Oxy-fuel gases used include oxygen, acetylene and liquefied petroleum gas (LP Gas); last two provide the high temperature Preheat flame.