Where the reflections of the lights are concerned I would expect them to be exactly on a line between the observer and the source. In this image they are perpendicular in the left half of the frame and tilted clockwise in the right half of the frame. I would expect any tilting to be symmetrical about the centre line, which suggests that the whole image is tilted clockwise.

If true horizontals are hard or impossible to find, an alternative is to look for a true vertical at or near the centre of the frame. In this case it's easier to balance the tilt of the verticals in the left and right halves of the frame (which is easier than trying to adjust to one indistinct central vertical).