Not all slideouts are equal. There is much variety in the construction of slideout rooms and in the mechanisms that move them. There is also a lot of variation in how they are sealed, open and closed, and how well they get wiped when retracted.
Slideout walls might be the same construction as the rest of the motorhome, or they might be of lighter construction. The box that moves may be totally sealed, or it may be open at the bottom. It might drop to be level with the floor, or it may stay above the floor. It might ride on rollers and be supported when traveling to be usable when in, or it might float above the floor and supposed to be empty when not extended.
Mechanisms might be hydraulic or mechanical. Mechanical mechanisms have included cable-pull, rack and pinion, and screwjacks. Hydraulic mechanisms might be separate each slideout or might act on all slideouts at once; a friend has a RV with five slideouts on a single hydraulic system, and in order to use her kitchen she needs to extend all five slides, as the kitchen is the last to move. The mechanism that moves the slide might support it, or it might not.
You are not likely to find many 30-35 foot type A motorhomes without slideouts, less then 10 years old. You might have to go back 15-20 years to avoid slideouts in type A. You will find Cs up to about 30 feet without slides, because these are made for the rental market where features that complicate the RV experience (slideouts, awnings, sometimes generators) are avoided by rental companies.
