The Vaastu Sastra applied to the palatial houses of the upper castes and to temples only, in the olden days. The very first requirement of the Vaastu is that any construction must be on a perfectly square plot and all other kinds of rectangular or irregular shaped plots are all to be rejected! And the Vaastu Saastra of old Travancore dealt mainly and mostly with residences of the type of the old Namboodiri "illams" with 8 or 16 very large rooms plus all additions such as cow shed/s, well/s, shed for fuel wood (விறகு புர) and also the temple for the family's "kula deivam" etc. The kind of plots involved in such cases used to measure quarter hectare or something like that!
Agrahaarams do not satisfy the Vaastu requirements at all; they were the result of an "alien" TB population which was trying to find its foothold among the non-TB people and devised this new concept of "aggregated living" and also sharing cost of walls, etc. Since the original agrahaaram houses were very large, there was not much of loss of privacy as it is today when the original "one house" has been divided over the generations into 8, 10 or may be even more! As for good luck/bad luck of residents in agrahaaram houses, the two happened when they were fated. Sometimes the partition of the house, length-wise was blamed for ill-luck.
Modern Vaastu is a money-making trick and aims at combining some aphorismd of the old vaastu along with Feng Shui and other similar belief systems around the world, and those who believe shell out the money!
Commodes in the latrine can face any direction, but, generally TBs prefer not facing east because it is the direction from which the "Sarvasaakshi" Sun god rises in the morning and we do all our poojas, japams etc., with the deity facing east.
