Sticks and staples refers to the tendency of many RVs and some to be very cheaply built and severely lacking durability. Many RV manufacturers use the cheapest possible materials in their products. Other terms include "toothpicks and popsicle sticks".
Low build quality may be okay for those who only use their RVs for a few weekend trips every year, but someone living full time will be repeatedly disappointed by things breaking. A self-built conversion or a professional conversion may be a better option for those seeking durability and quality. Some RV manufacturers do offer higher-quality products at the top end of the market, with vehicles often costing over $250,000.
A similar-sounding term is a sticks and bricks residence, but it means something else!