As per Bava Kama 20a, a squatter who does not benefit from a property, where the owner does not lose anything from the squatting, need not pay rent. Rashi explains there that the squatter is not considered to benefit from the use of this property because "שכיחי ליה בתים בחנם" -- he has houses available for him to use, free of charge. I assume that this particular case is an instance where the squatter's access to the other houses is legal; an earlier comment by Rashi refers specifically to borrowing and owning those other houses.
What if the squatter does not have legal access to any houses, but has access to two houses (that are not generally rented out) as a squatter? His free access to House A is predicated on his free access to House B, which in turn is based on his free access to House A. Is this man able to use either house for free? Is there a problem if the reasoning allowing him to use these properties is circular in nature?