I've never understood this complaint. Almost all special effects are obvious, because they depict things that aren't real. I don't remember watching Ghostbusters in the theater and wondering if those were really ghosts.
Some people just cannot (or refuse to) recognise all the noise you can see around old/cheap/low quality effects. I often watched those silly Japanese horror varieties where they would show you a grainy video of some dark place, and then maybe a grainy shot of someone crawling out of something. But you know it's two separate things spliced together because the grains are of a different size, or when one area is gray-scale while another is simply decolourised to match. My friends could never tell the difference.
Older 'practical' special effects still hold up better than much more recent early CGI though. Even if you can tell that something is a physical model, IMO it still looks 100x better than a poorly rendered and animated low-poly 3d effect.
I've never understood this complaint. Almost all special effects are obvious, because they depict things that aren't real. I don't remember watching Ghostbusters in the theater and wondering if those were really ghosts.