I remember when I used to get annoyed with cazadores, I would be shouting f*cking cazadores constantly while trying to fight them. What makes them hard to deal with is there spastic movements and their poisoning. As others mentioned above, old world blues DLC makes them non threatening. The heartless perk makes you immune to poison and DNAvenger (or was it DNAgent? I get them mixed up),a 3 level perk, gives you a massive damage boost on them. I remember one time I went to that place where they made fake bottle caps and I saved my game there after not saving for a good hour or so, I come out and there were 6 cazadores outside waiting for me. I let boon get gangbanged and I bailed like crazy. At low levels, avoid them and heal yourself with antivenom if you get stung; legionnaires tend to have antivenom on them.