I guess it must obviously work or they wouldn't continue to do it. I've only ever had the real high pressure a few times. I've never had any problem walking away because for me, it is always just business.
I did have fun with one car guy. Told him right up front that I was just looking right now to gather information (this was before you could just look up everything on your phone) for a later purchase. The hard sale was on at that point. After repeating a few times that there was nothing he could do to close the sale that day because I was still researching and had not decided on exactly the vehicle I wanted, I just started talking slower and slower to him. After a while, he actually asked if I was feeling ok. I told him I was fine, but why do you ask? He just said I seemed to be talking very slowly. So I told him that I was talking slow for him since he didn't seem to be able to understand what I was telling him about me only looking and would not be purchasing that day. He didn't find it nearly as funny as I did...
I ended up buying the model he was trying to sell me from another dealer. Later, the sales manager from the first dealer followed up with me to see if I was ready to purchase. I explained that I had purchased from another dealer and primarily because of their sales tactics. He just kind of mumbled something and hung up.
Be it cars or RVs, some of these places seem to forget that they are not the only place you can get the car or RV you want.