I poked around the JSON files, and out of 11 prisoner-type enemies and 5 guard-type enemies listed only 3 from each group can initiate a blowjob (i.e., tagged PoseStart instead of PoseJoin). Not sure I have the smarts to check whether all 11 prisoner-types can spawn on Floor 1 from the get-go, and if not - how to tell them apart (same for guards), but if all of them can spawn...if I want to keep Karryn an undefeated virgin, it seems I have a lottery to win (or just edit the skill in).
Cum facials appear to be limited in a similar fashion: for example, only one prisoner-type enemy has the skill attached. At least some of the thugs and goblins can use it, too.
Nice work, maybe I can help out here.
TL;DR: Win the guard battle twice or get the "Self Paid Equipment" edict and you're good to go (i.e. guards spawn in this battle that can initiate bjs).
Now, let's get to the details.
The easier of these two groups first: the
guards in the guard battle.
As most already know, the type of guards changes depending on guard aggression which can be increased by fighting the (smoking) guard battle (increase by one) and by edicts (increase by more than one) and can be decreased (by one) only by losing the guard battle (this only negates the increase for starting it). Currently it is capped at Karryn's max level limit + 10. Thus, without clearing floor 1 the max guard aggression is 22. Let's look at the function that determines which guards are encountered:
The three guard types that are able to initiate bjs are lv2, lv3 and lv4. For every enemy that is supposed to appear in the battle a random type is chosen depending on the aggression level. Example: If the aggression is between 12 and 15 only guards that are able to initiate bjs are chosen. We can see that starting with aggression 5 we can get bj capable guards and even if the aggression reaches the maximum for floor 1 (i.e. 22) we still have a 50% chance per guard that he can initiate bjs. This shows that we can reliably get the necessary enemies without clearing floor 1.
Now to the previously mentioned three
prisoner type enemies that can initiate bjs.
(Some background for those interested: If want to get an idea how enemy ids and enemy troops work, look for my tweak regarding enemy troops. The enemy ids 58 and 61 are not used at all currently so there is only one enemy (with id 55) that can engage bjs.)
Now without going much into the details, I've looked at the enemies that spawn in each room (depending on order) and no room has a group containing the relevant prisoner type. So theoretically the "bj prisoner" cannot be met in normal floor 1 anarchy combat.
NOTE: All info relevant for v0.7B.p. Also, I remember that in the past I noticed some randomness regarding the enemies encountered in the normal battles. So without knowing more it may still be entirely possible that these prisoners can spawn, but I don't know how.
EDIT: Just tested it, it works fine in guard battles.