one of the main issues is whether you are getting 30 amps of power from the 30 amp outlet. ive stayed in fairgrounds, old campgrounds, and behind fire stations, and used electric at fmca/good sam rallies. . just because you have a 30 or 50 amp outlet doesnt mean you are getting that amount of amperage. old undersize wiring, too many people on the same supply gives you less amperage. 10 people on a 50 amp service line cuts the available amperage way down. if i have a choice, i use 50 amps everytime. while i may not get the full amps, i at least get more than 30.
everytime i get asked by a campground "how old is your rv?" i ask how old is your campground. if its older than 10 years, i ask when they upgraded their electric. especially in the summer. its important to me, maybe not to others.
if they cant answer, i move on.