I have also found that the 50 amp receptacles are normally in much better shape, mainly because the average RV can draw 25 amps with the A/C or electric heaters working. Enough to melt the insides of a 30 amp receptacle, but plenty of extra capacity on the 50 amp one!
I have also found that most RV parks with only 30 amp receptacles also need a voltage booster in the summer time to get over the 105 volts found on a warm day - when everyone else also wants to run the A/C unit.
Most of all, complain, and tell them that you will need another site - if they can not send someone to replace the bad receptacle. Also remember to shut off the incoming power breaker (if you can) before plugging in, or unplugging, so that there is not a 10 amp spark across the receptacle end when you plug in or unplug. You can always shut off your main 30 amp (or 50 amp) breaker in your RV before unplugging, and leave it off until you have already plugged in and are at the next campsite. This will stop the sparking on your power cord end.
Yes there is always a load on your RV - even if it is just the battery charger. . .
Have fun camping!
Fred.