Is it wise to keep MH plug in to Electric?

With most modern motor homes I would say leave it plugged in as much as possible. this keeps batteries up and ready to roll at any time. In many if not most motorhomes it will keep both Starting and House batteries full up and ready to go.

Ours has been plugged in 24/7 for 17 years. No issues.

Your profile says you have a 1995 dodge MH and unless the converter was upgraded along the way it is probably not a multi stage charger. I would check the output of the converter and post what you get here, some can be close to 14 volts. If so I would not keep it plugged in all the time, just plug it in until it is fully charged then unplug and use the battery disconnect switch and when the battery voltage drops by 10 percent plug it in again. A good battery will last all winter without being plugged in. Also your op says you have a 454 engine but your profile says Dodge was this a mistake?

I see no advantage either way, except a nice warm spot for critters to nest. I,m in ohio, rv in a garage ,batteries on a tender , rv winterized.

My motorhomes stays plugged in 24/7 with no ill effects and I've been doing it for the past 9 years with 3 different coaches. If your coach has a quality charger, you'll be fine leaving it plugged in.

I leave ours plugged in for humidity control but I leave the fridge off with the doors open.
It frosts up in a few weeks.

I've been RV'ing since the 60's. I have always kept my rv's plugged in and the frig running. I winterize during the winter and the rv is ready to go camping on a moments notice. I have never had a frig go out due to it running 24/7/365, never. I just made sure the converter doesn't boil out the batteries in the old days, not the converter shuts off when the batteries are fully charged

I keep our 96 Southwind plugged in 24/7 when parked in our yard.

In the last 5 years since we've owned our rig, I've had it plugged in for the majority of the time....either sitting in the driveway or at a campsite. When I store for the winter in December, I turn off the main battery switches and the rig sits under cover at a storage lot until I de-winterize just before Easter. I've had no problems as a result of keeping her plugged in.

in the months i use the rig all the time, i leave it plugged in and the refer on with stuff in it. in the winter, i unplug the rig xcept for about 1 week a month just to keep the batteries up.