I always understood "Bogart" to mean letting it hang from the lip while not actually smoking it (i.e., in between puffs), which is exactly what Humphrey Bogart did in the movies. This is different from getting the end all wet. In fact, if it gets too wet, it won't stick to the lip a la Bogart. The sin of Bogarting, as indicated by the song's lyrics, is depriving others of the opportunity to get a puff while one is in possession of the smoke but not using it at the time. It's true that one can hang onto it in his lips in such a way as to saturate it. I would call that slobbering rather than Bogarting.