Used as an adjective:
When someone (particularly a picture of someone on the Internet) has a hotness level inversely proportional to the skill level in photoshop it would take to make an average person reach that level of hotness.
This is best used for profiles on dating sites where the person has had 'professional' photos made for their profile.
You see someone really hot on a dating site, and your friend tells you they are about a 8 in terms of being Internet Hot, which means it would only take someone using Photoshop a skill level of 2 to make them that attractive.
Internet hot is the term used when you see a person online whom everybody will say is hot (cute, pretty, etc.) but really isn't, they are just hot enough for certain weirdo's to become "excited" over, on the Internet but not in a real life situation.
Swaggy Justin Bieber look-alike: Ayee girl ur sooo beautiful !! u hav the prettyest eyes evr !!! want 2 txt nd trade pix???
Regular guy: Pshhh.. Internet hot. Never would bang her in the real world.