Called a lawyer friend who put me touch with a immig. lawyer in Miami. He said they use the term "intending immigrant" for people who try to circumvent the laws and basically live here. Its done on a case-by-case basis. Its up to the visa holder to prove to the immig. officer the need for his quick return to the U.S. The attorney also said staying the full 180days on a regular basis with short stays home will red-flag you and you better have really good explanation for why you need back in so quick. He said that there is no set-in-stone % like the 65% mentioned earlier but that a lot of immig. officers use that as a rough guide. Said until 9/11 this hardly came-up but after that things changed big-time. I agree 100% that this is beyond vague. If they want you stay home a certain amount of time between stays it should be clearly stated.Even though he had a series of 6 month visas, which he complied with by leaving the country after each 6 month stay in the US, apparently there is an unwritten rule that you cannot spend more than 65% of your time in the US when using 6 month visas.