So here's a few filters that I've generally used when it comes to teh wimminz. Bluntly, these types are not fuckable in my mind:
* underage or far younger than I am
* stunningly good-looking
* dirty/filthy (physically)
* drugs (prescription or illegal)
* medical issues (physical, like being gluten-intolerant)
* crazy (NPD/BPD etc)
* heavy/visible tats
* piercings (especially tongue/nipple/clit)
* excessive jewelry
* career girls
* any whiff of feminist mindset (which is damn-near all of them)
The reasons range from direct health (cigarette smoke makes me nauseous plus messes up my lungs and makes me susceptible to bronchitis - borderline asthma and hayfever is a bitch), through lack of interest (underage doesn't turn me on), through to emotional and mental and physical self-protection. As you can imagine, 99.9999999% of girls do not make it past these filters.
The few who I've made exceptions for and let through have invariably caused me way more hassle than it's been worth.
In many cases, a girl passes the visible filters and then opens her mouth and the red light starts flashing with the klaxon "AVOID! AVOID! AVOID!" going off at 120+ decibels.
Most of these things are self-evident to any thinking man. A few need some explanations:
Stunningly Good-Looking: In my personal experience, every girl that I've met who was an 8+ has been seriously crazy in some manner (entitled, BPD/NPD, whatever).
Crass: If she has a worse potty-mouth than I do, it's a boner-killer.
Medical Issues: It's a flat-out downer trying to go out with a girl who is incapable of relaxing freely and doing the things you can do (fat girls just can't keep up physically with my lifestyle, gluten intolerant girls have to be anal about what they eat, etc).
Excessive Jewelry: This is a signal that she's on the prowl, all that jewelry is something shiny to attract the attention of Men. It's also a sign of self-centered narcissism and indiscriminate (often bad - like shitty tattoos) taste.
Pants/Shorts: Great way to signal that she expects to be the one wearing the pants in the relationship - thank you Feminism. Girls in short-shorts are also sluttifying themselves up. Especially watch out for camel-toe, it's always deliberate.
Career Girls: Apart from the deeply-internalized "you can have it all" message from Feminism, she just can't keep the career attitudes out of her private life. She might act absolutely submissive in private, yet you'll be surprised at how quickly a shit attitude can show up when she gets annoyed.
Make your own filters. The more strict I've gotten with those filters, the gladder I've been as my life is less-disturbed by bullshit from women and what they laughingly consider relationships.