let's remember what the herpetarium was named after

Lizard Demographics
Demographics with an extremely high correlation to Lizardness. None are essential for the definition but all are usually implied when the term is used in relation to internet culture.

Class

Lizards are unanimously lower class. While it is theoretically possible for a Lizard to become wealthy through dishonorable means, exploitative arrangements or winning games of chance a Lizard will never ever earn enough honest money to improve their situation. It is also possible for someone born into a well off family and still be considered a Lizard if they were still of low cultural or social capital and displayed lower class behavior. Financial irresponsibility and failure to plan for their future are hallmarks of the Lizard condition. While a Lizard is usually very poor it is more the level of scummyness, or "scaffyness" in Scottish, than their current level of resources that informs their lower class status. Lizards are usually unemployed and dependent on lovers or the state for living expenses or have very low skill level jobs such as stripping or house painting.

Race

All documented Lizards have been Caucasian. In theory there is no reason why a non-Caucasian couldn't be a Lizard but it just doesn't seem to be the case. Perhaps it is because quality of life in white nations and communities is on average the highest in the world so the worst examples of the white race have less of an "excuse" as they usually have it easier than other cultures and stick out more. Most Lizards are very racist and criticize other races for being dishonest and failing to contribute to society, ironically exactly how they themselves behave. This is "projecting", a common process with Lizards.

Age

Almost all documented Lizards have been 35 years old or older. This may be because the average human life span in modern day developed countries is approximately 70 years old and in the first half of the life of someone with these negative traits there is still the possibility of turning their life around, but once a person is into the second half of their life it is far more likely they will be stuck in their ways forever. If there is even a perceptible chance of changing, "growing out of" or "cooling down from" the negative personality traits associated with being a Lizard then they cannot be truly defined as such until there is effectively no chance of change. The outdated vocabulary and creepy out of touch vibe is an important part of the Lizard. However there has been one exception to this observation, it became readily apparent that subject "rootbeer" is a Lizard a whole decade before the regular age cut-off period.

Country

A Lizard can be from any first world country, or really any country within their own social contexts, but so far they have almost all been exclusively observed on the internet posting from either America or Australia, the two worst shitholes on Earth. Africa doesn't count because it's actually a portal to hell. All three start and end with As though. Makes you think. One Lizard, Rose West, is from New Zealand, which is basically Australia anyway.

Gender

A Lizard can be male, female or even transgendered you shitlord. There is a noticeable overlap in their malignant behaviors. You may assume that using sex for leverage and spreading gossip is a feminine form of dysfunction and physical violence and intimidation tactics are masculine, but Lizards of either gender have no problem employing any and all of these tactics

Lizardness as a Sexually Transmitted Infection

The seemingly sudden transformation after mating with a Lizard of subject "rootbeer" into one of the worst cases of Lizardness ever recorded lead leading herpetologists to theorize that Lizardness can be transmitted via sexual intercourse, but further research has concluded that the subject was already a Lizard and his intimate interaction with a fellow Lizard simply brought attention to his Lizardness. This does not mean that sexual relations with Lizards is safe for humans and is still STRONGLY advised against. It also brings attention to the startling reality that a Lizard does not need to be an outsider attempting to infiltrate your community, they could already be there and yet to be detected. Never let your guard down to the Lizard menace.