The Thugs in Little Mahakam (the non-human district) spawn rather randomly, mostly between 9 pm and 2 am, in your first night there, you might encounter four of them, but in subsequent night, the rate may drop, sometimes, you will have absolutly no encounter, sometimes you will meet fleders istead of thugs. As I experienced, beside the quest for Carmen ("Working girls"), you have a maxium of six encounters per night, two of them in this case beeing fleders (most appear in the hospitals garden, some near the Hairy Bear, rarely in Little Mahakam, at both ends of the main street, more likely in the litte corner near the little gate there). The relation of slamandra to thugs seems to be set at one slamandra to three normal thugs, but I can't say that for sure. If you don't get enough badges on quest or the previous encounters, you will have to try in coming nights. Best guess to get them would be starting patroling Little Mahakam at 8:30 pm, once you have encoutered a thug, loot him, run directly to Thaler (cross the garden and take down the fleder if one spawns), sell what you don't need and head back. If you haven't got badges try the next night - you can still use the remaining night time to poker with Thaler and make some money.