Grunge music has what has been called an "ugly" aesthetic, both in the roar of the distorted electric guitars and in the darker lyrical topics. This approach was chosen both to counter the "slick" elegant sound of the then-predominant mainstream rock and because grunge artists wanted to mirror the "ugliness" they saw around them and shine a light on unseen "depths and depravity" of the real world. Some key individuals in the development of the grunge sound, including Sub Pop producer Jack Endino and the Melvins, described grunge's incorporation of heavy rock influences such as Kiss as "musical provocation". Grunge artists considered these bands "cheesy" but nonetheless enjoyed them; Buzz Osborne of the Melvins described it as an attempt to see what ridiculous things bands could do and get away with. In the early 1990s, Nirvana's signature "stop-start" song format and alternating between soft and loud sections became a genre convention.