Scents headache

Could someone explain the scents mechanics? I know a lot but got a total mess in my head now 
If i commit a crime it leaves the scents, ok, but do i leave more scents when i derp around, like bleeding animal?
Or only once in the place of crime?
(I'm wondering about the blowdarts but dunno what to do with the poisoncraft crime?)

If i commit a crime it leaves the scents, ok, but do i leave more scents when i derp around, like bleeding animal?

(I'm wondering about the blowdarts but dunno what to do with the poisoncraft crime?)