Based on this thread it seems a few definitions are in order. First there is free camping which is exactly what it seems to mean - camping without any fees. Boondocking is used to refer to camping in remote areas. Sometimes it is free; other times there are charges or permits needed. Usually this means no facilities, but not necessarily. Next there is stealth camping. That means keeping a low profile so passers by do not know anyone is staying overnight in the RV.
Some people seem to feel one or more of these is illegal and they might equate stealth camping with illegal activity. There are lots of reasons to stealth camp even when staying overnight is perfectly legal. Whenever I stay in a populated area, I try to employ some level of stealth camping as a courtesy to the neighbors. If I stay at Cabelas or Walmart or Cracker Barrel or the like I keep a low profile: no awnings, no lawn furniture, no generator.
Then there was a landowner who was upset that someone would try to stay on their land. That is a situation which can be easily rectified with a $5 sign. In fact you better watch out if you have private roads that are unmarked. They can be deemed public if they are open and not posted.