On the grand scale of things a single webmaster is not going to have people that want the site now, dont' buy, and come back later by typing it in and join. The % of this would be so low that you would never notice it. A very large traffic sending webmaster, may have a higher chance of this happening.
You have a higher % of surfers that right click, copy link location, paste in the URL bar and remove the referring ID. Which is still a rather low %.
On pretty much any program if a visitor clicks bookmark it saves the webmaster ID. Most programs that have BOOKMARK NOW writin on the site also pass in the webmaster ID.
The largest error a webmaster will have is from people CHANGING the url in the browser.
Once you are on my tours the URL bar has a linking code that looks like.
http://www1.bustyamateurboobs.com/01/?nats=MzoyOjI
The % of surfers that REMOVE the 01/?nats=MzoyOjI and go back to the warning page is crazy. Our program keeps track either way, MANY don't.