Spraying moldy surfaces with bleach can work, however the surface must be solid and non-porous. Counter tops, certain tile floors, bathroom tiles, glass etc. can be cleaned this way. The grout between tiles, walls or any porous surface or wood-based building products, including paneling, studs, etc. are not candidates for chlorine based products.
There are a number of new mold and mildew related products on the market, and each have their own unique instructions and intended effects. Read the product label carefully to make certain it is appropriate for your particular problem and then follow the directions exactly. This is the only way to be certain your efforts have a chance for success. Of course, calling mold remediation professionals when it come to mold remediation is always a good alternative to the “hit or miss” reality of do-it-yourself attempts.