Here is a site rec:
The Tough Guide to the Known GalaxyIt's a
rip-off of homage to Diana Wynne Jones's
The Tough Guide to Fantasyland; it's hilariously funny and very true.
A few examples:
2) Aliens with Forehead Ridges. Much more common - especially in HOLLYWOOD SCIFI - than Really Aliens, these are species that look almost exactly like Earth Humans, except for some distinguishing visible feature such as, well, forehead ridges, or odd-shaped ears, or whatever. Sometimes they look rather less like humans, in which case (if friendly) they often resemble large teddy bears. *coughEwokscoughWookieescough*
...Aliens with Forehead Ridges have become much less common in written SF (save for media tie-ins) than they were some decades ago. In written SF, the KNOWN GALAXY seems increasingly to be inhabited only by Earth Humans. However, Aliens with Forehead Ridges continue to thrive in Hollywood Scifi. This is for an obvious reason: the audience wants aliens of some sort, and Aliens with Forehead Ridges are the only kind that can be played by members of the Screen Actors' Guild.( Cut for length )I do have a pet theory that the militarist SF subgenre is because the authors really want to write about a navy, but the historical one requires tedious research about Jutland or the Napoleonic wars or the Atlantic convoys in WWII, so you borrow the ranks and ship classes, move it into space and the future and voila, you can make up the rest. JMO, of course :D
I don't need to talk, as I read anything from space opera through Hornblower in space-type stuff to hard SF. The thing about the more "soft" end of the spectrum is that if the science is all hot air and handwavium anyway, it doesn't date so obviously (what
ajhalluk (I think) calls the 'slide rule phenomenon'—1950s SF writers didn't foresee the advent of computers).