The Best Little Birdhouse in Texas-I mean NY!!

I have many, many birdhouses presently on my property as well as some that have fallen apart and are gone. Probably about 4 years ago, I bought a bluebird house and nailed it to a telephone pole. It's painted brown and has yellow flowers stencilled on each side. Someone warned me that the birds aren't going to use this house because it was painted and wouldn't 'smell' right to them. I planted clematis at its base and put a wooden trellis with a couple of hearts carved out leading up to the house for the climbing plant to latch onto.
Well...let me tell you that it has had the highest occupancy of all nesting sites -both past and present houses. It is a proverbial bird factory- not bluebirds but that doesn't matter. There are non stop residents and they don't seem to care that it hasn't even been cleaned out. New twigs and straw are angled into the opening, and the next thing you hear are the peeps from within. Next you see their little beaks at the opening and the parents are providing breakfast! And very soon, little birds appear at the regular birdfeeders, and new birds are moving into The Bird Motel. What is the major attraction of this house?
I wonder if they have cable and phone service from the lines that bring these services to my house!!
Whatever! It is very entertaining to watch their activities and so far no birds have dive-bombed at my head when I am right there in their faces. They must sense that I won't ruffle their feathers, or they know that I am too big to move in and take over.
In any case, I'll bet it's the move-in condition of the house...and the fact that they don't even have to do any painting!!