First off, the caresheets at "lizardcaresheets.com" are questionable at best. Their argentine tegu guide says "UVB needed" whereas the colombian tegu and many of the monitor caresheets say that UVB is not needed because "they get calcium from rodents". Reptiles (generally) need UVB to convert vitamin-D into the active form D3. Without D3, the calcium never gets metabolized. Just because the domain has "caresheet" in it, doesn't mean anything. I would take anything from that site with a grain of salt (or less).
As to reptiles "liking you", sure, why not? To "like" something or someone is little more than forming an association between that thing and a positive stimulus. The human version of "like" is only different because humans can blither on about it. Also remember that intelligence is a range, not a fixed value. Like mammals, the smartest are a hundred times smarter than the "dumbest". The smartest lizards (tegus/monitors/iguanas) are sometimes considered to exceed dog intelligence. Just because you don't know how to read its queues (it can't smile, purr or pant) doesn't make it stupid.
http://en.wikipedia.org/wiki/Monitor_lizard
Now, in all fairness, nile monitors are probably one of the most difficult reptiles to tame. They're also cheaply imported and sold (and the only way to make money from cheap sales is with quantity). Low price, "cool looks" and motivated sales staff means alot of these poor animals find homes with inexperienced keepers who have no idea what they're getting into. Nile monitors are expert escape artists, nervous (you would be too if you shared a river with crocodiles), highly intelligent, blindingly fast and very aggressive (when nervous, which is often). They also grow to 7 feet in length and are always hungry. A tank large and sturdy enough to hold an adult will cost you a fortune, as will the food. Chances are the sales person didn't mention much of this... (or the parasites)
Taming a nile takes alot of patience. Be prepared to observe and/or work with your new pet every day for 3 to 9 months (roughly). Learn when to leave them alone and give them space. Realize that your new responsibility (yes, responsibility) may never become tame. Having a large, fast, cunning animal plotting your demise every time you clean his cage is challenging at best. Again, if you don't have experience with "semi-aggressive" animals, you've got a pretty slim chance with these amazing monsters.
Savannah monitors, the de facto "starter monitor", can also be challenging and feisty, but they frequently become dog-tame. Nile monitors are much, much more difficult, and forget the coolness factor. When they're hissing, lashing and lunging at the cage glass, they're not "mean and fierce", they're scared out of their wits. Terrified because some huge ape is poking the glass, maybe about to eat it.