There's an Isuzu pickup at my work and the drivers almost always rev it after starting it up, it's really hot here too so it has no issues turning over, compared to colder environments I guess. Anyways is this bad for the pickup?
Revving any engine, diesel engine for locomotives, ocean going ships with huge diesel engines, aircraft engines, car/truck/suv gasoline or diesel engines are not revved when they're cold for several reasons. All internal combustion engines need oil lubrication immediately upon startup. Oil pumps take time to pressurize the oil galleries to begin lubricating camshafts, crankshafts, lifters, etc. Engines using turbochargers also pump oil into turbocharger shafts. Since oil takes time to start lubricating moving parts, its never recommended to rev engines but allow them some warm-up idle time before racing to the first stop sign or light. Cylinders are lubricated with a thin film of oil and if oil drains off then metal to metal contact occurs and can result in scoring, eventually leading to lowering compression from continually revving an engine after starting up. This won't happen immediately but accumulate wear until startup results in a smoking exhaust. Train engines are huge and never revved, allowed many minutes of warmup time before hauling itself and loads. The same with ship engines. No one reads of captains or shipmates revving ship engines after staring them. Formula-1 racers rev their engines because those engines take a little longer to warmup and don't idle very well when cold so revving keeps these engines from stalling. Once started up and cleared to run, racers drive off to help the engine reach operating temps at low speed before the actual race begins.
For everyday driving vehicles, revving isn't recommended right after startup. Driving immediately after starting warms up the engine faster than revving in place.