I understand what you mean; But listen, our minds can easily be tricked into believing into stuff while we look at different patterns. afaik; our eyes can only handle 60FPS and no more. If it was a CGI alien you'd think "ok, this is definitely fake. It's too slow for the eye and there are many details that differ it from an actual human being. Because when we move out lips, alot of muscles move at the same time, our facial expression changes, the skin on our face moves on all sorts of directions. On a cgi humanoid-alien you would notice that the movements are very unrealistic. "
BUT if you look at a "dripping" effect, you will have a hard time differing it from reality because the properties of that effect can easily be programmed. Parameters that it requires are "gravitation","speed","velocity"(,acceleration)... and ofc fps above 30.