Do all campers leak ??????

Campers are a upside down boat
Bust
Out
Another
Thousand

Campers CAN leak but not all actually do leak;

My last 3 campers have been water tight but then I do keep then in a barn
to protect them from the elements. The sun does a number on the rubber roof
so I prefer to protect the roof.

Also an annual maintenance of the roof is almost required.

If you find a camper that is covered, it may be a good sign that the owner
cares about their RV and may be in better condition to owners who leave them
outside.

If you buy an RV you're gonna have to Maintain it and yes, unless you are a DIYer, you're gonna have to pay a penny, especially for labor. So this is the point where you ask yourself if you can take on another "bag of Expenses." UV rays and Oxidation are killers, it would be nice if I could keep My Moho tarped or covered at all times, especially in the S.Texas or Az or Nv sun, but CG's don't allow it, so yes get ready to recaulk every 6 moths to a yr, and reseal every yr to 2 yrs. If you're not a fulltimer and you keep your RV in a garage you may be able to extend the recaulking and resealing intervals.

They all can leak. You need to keep up with the inspections and maintenance. The roof seems to be the most vulnerable area.
However, they can leak at other seams or around openings.

Most cover their RV to help keep it clean and protect it from sun damage. But a cover also helps keep it dry.
Don't let the possibility of a leak keep you from buying.