Indoors, position is everything. I have been placing my antenna just about 8 or 9" inside a South-ish facing window, and getting variable signal strengths. During the day, up to 6, in the night down to less than .2, even with antenna tilted 51 degrees at 178 degrees, according to the sat finder. (San Antonio, TX)
Last night i scooted the antenna right up to the window, pointing several degrees East of straight South, and signals jumped to 3.5 - 5 and stayed there. In other words, it worked better pointing straight through the glass, up close, but not directly at the satellite, than it did pointing at the satellite, but several inches from the glass.
Things that will kill reception are the freezing rain on trees, and metal window screens or solar film on the window.