What are your determining factors for targeted followers?

Where I won't lie I did not search the forum very hard at this point. I wanted to bring up a conversation on how you determine whether someone is worth following or not worth following. Obviously the point is to gain or get involved in a relationship with these targeted followers to potentially sell a product and or cross sell or promote a product not specifically in our niche. More some general rules of thumb that you would suggest?
Appreciate any input or advice in advance.

AdMissile

No ones willing to chime in?

There are plenty of tools that help you filter these things nicely. Personally I've never been a fan of Twitter, but I'd follow someone who:
Has been active within the last couple of days
Has a profile picture
Doesn't tweet spammy links or look spammy in general
Doesn't send automated messages upon following
Has tweeted recently using keywords related to my niche
Doesn't have thousands of followers/following

Something like that. I'm sure someone more active on twitter could provide more in depth suggestions than me though.