The ones that are able to be seen look good enough - there is wetting on both sides of the joint. The standard test for determining what you want is called a "red dye" test. Red dye is flooded under the part and left to dry, then a one pound or so weight is mechanically attached to the top of the device (via string). The board is secured in a holder with a pulley system over the top, then the weight is suspended off to the side. Over time, the part is slowly pulled off the board, leaving red dye in areas where solder should be. This is the only test I know of to verify solder joint viability.
The red dye test is considered a destructive test, although sometimes the part comes cleanly off the board.