I get it. It's a fun silly show with very light science elements (VERY light). But what bugs me is the boy being able to see his, "True form". The alien was actually able to physically alter himself into the Dr. There is no illusion or disguise for the boy to, "See through". He should look like that Dr. to everyone because he physically looks like him.
shareIt's a remnant from the source material where he would mentally project the image of a human into other minds and some people were resistant to such mental manipulation. SyFy really doesn't know what they're doing and just duct taped this mess together.
shareAt the risk of sounding like an apologist, the alien was substantially taller than Harry when he first invaded the cabin. It showed the alien reducing his height and reshaping his feet prior to the more superficial illusion of disguise that came next.
This is a difference from the source material in that the alien was of usual human male height and build prior to taking the on his human appearance. We also never see the human appearance of the alien in the comic book. In the comic Harry also appears as his alien self on camera unlike the TV series.