As a rule of thumb no laser whether rotating, line or fixed dot is truly visible outside in all lighting conditions over any great distance. If its full sun over more than a few meters you are not going to see anyones laser whatever the colour. The darker the conditions the more visible a laser is. For reliable use of a laser outside buy a laser with an electronic receiver. The receiver will “see” the laser for you in all lighting conditions at the range specified. Indoors, visible lasers become much more of a proposition as lighting levels are generally lower and you have some control over it. In these indoor conditions a class 3 green laser is far more visible than a class 2 red laser by up to 4x. Note that a class 3 green has a fraction better visibility compared to a red class 3 laser due to the similar power output.