Nava It looks to me to be a very rough texture, as we call it here. If I understand you correctly, you would like the walls to be smooth. I would advise against trying to scrape it, and it is not worth the effort/labor to try to sand walls that likely have several coats of paint.
What we do when a homeowner wants a smoother wall that has a heavy texture like you are describing is “skim coat” the walls with drywall mud (very labor intensive also) to make them smooth. then we would texture and paint according to the customer’s specs. Forgive me if I misunderstand you.
THespos I think the home improvement shows are great. They give DIY types sound ideas and also show that some things we do are actually quite skilled and sometimes you do really need a pro.
dahfisheroo Since you signed the bid last week and gave me 15% up front for material, it will actually be 3 or 4 weeks before I can get somebody out there to start the work. Dude, it’s summertime, I am spending time on the boat fishing. 
scotandrsn If you are installing baseboard over true plaster walls (some people call drywall plaster) plaster can be up to an inch or more thick, making nailing it a problem. Not sure where the carpet dude was coming from, but standard practice is to use finishing nails, #6 for most base like streamline, the smooth stuff, or colonial, which has a couple curves/grooves. The nails are countersunk into the material (I generally use a pneumatic nail gun) but by hand, you drive the nail almost flush with the material, then use a nailset to sink it in a bit. You want to nail into the shoeplate framing which is 1 1/2 in thick from the slab, so, counting carpet/tile, etc, try to nail an inch or so from the bottom of the baseboard. With true plaster, you might have to use longer nails, also maybe into the studs, which are generally 16 in apart, or in older houses 24 in.
If it is an old plaster house, with wavy (not straight) walls, you sometimes have to glue and screw the baseboard. Just general advice, without more info.