Was at a campground helping out as the 'handy man' once and was asked to go check the 30 amp plugs to see if they were needing replacement as it had been a few years since they were checked. The campground had just under 140 sites. I ran out of plugs at the 30 mark and they went and got another 2 cases. I ended up replacing about 125 plugs. They were burnt and cracked, allowing the rv plug to get hot and get damaged too. I suggested they check them more often and buy another case of plugs, just in case.. That changed how I looked at the parks plugs when I went into a new campground. Looked to burnt or cracked areas before I ever would plug in, and if found i asked for a replacement or another site.