Different folks, different strokes
If you are a familiar face and you visit a lot, you will generally receive good treatment from almost all the girls. I even do the occasional half hour rooms here and there, granted not so often, but I do take half hour rooms here and there. If I know I'm only doing a half hour (for example, due to timing constraints / logistics) and if I'm going with a girl already known to me, I almost always disclose this to my girl upfront to manage expectations. Some of my Oase girls still give me DFK in the half hour rooms, not all, but many still do.
It should be remembered that there is a lot of competition there and you can always go to another girl if one girl isn't agreeing to give you what you want. The girls know this and if you are hesitant about going to the room or walk away from an initial chat, many of them will likely be more accommodating the next time you approach them.
If you are visiting on a week day when business is slower, you should just walk away and say no to silly offers like 150 Euros for an hour. That's just ridiculous. No Oase girl has ever propositioned me for 150 Euros for an hour (this is actually against the rules there, unless the extra 50 is coupled with a service that is not included in the standard service -- an easy rule to circumvent with a bit of creativity to be sure, but it is actually technically against the Oase rules for a girl to proposition you for 150 Euros for an hour room that includes only standard service).
Another thing to keep in mind is that once you say "yes" to upselling to one girl, they will run and tell all their friends. Then, the situation will only become worse for you. All Oase girls already know I don't do extras, so they don't even bother bringing this up in the room -- they already know it would be useless to do so anyways. I can't even remember the last time a girl offered me CIM or anal in the room at Oase, including girls who I go to the room with for the first time. I'm pretty sure that their verbal version of ISG in the club is much more effective than our ISG.
Sometimes I wonder if some of these reports of upselling could be remedied by guys just standing their ground and not saying yes to all these silly propositions. Then again, it's hard for me to judge how the girls treat newbies since I have not been a newbie for a long time.
Anyways, I also have a choice of different clubs and I do branch out every trip and visit other clubs, but I always find myself coming back to Oase as my personal favorite. This recent trip, I visited Mainhattan twice, but the line-up was too small for my tastes. While I always appreciate their separated smoking room, I found their food to be more limited than Oase and Sharks. Mainhattan's facilities are great but again, I need a little bit larger line-up. I also visited Sharks twice this past trip and had a relatively nice time there. If I spent as much time at Sharks as I do at Oase, I would probably know more of the girls there and my guess is that my opinions of these two clubs would probably be reversed.
I do get annoyed about how uptight the non-Oase clubs are about carrying my cell phone around with me. At one point in Mainhattan, I was sitting alone in the restaurant texting on my phone, which was sitting flat on the table. I was completely alone in the restaurant, not a single other girl or guy in the entire restaurant. One of the cooks scolded at me for having my phone with me, so I put my phone away in my towel (no longer visible). Despite my phone being put away, the guy actually insisted on accompanying me back to my locker to witness me putting it away. The staff at Oase are much more polite and they realize when someone is using their phone legitimately versus inappropriately, instead of treating their customers like children.
Anyways, I know I've said this before about how much I enjoy Oase, but it bears repeating based on my recent experiences there.
This past trip, I also brought a friend with me from the States for a short portion of my trip, and I took him around to the various Hessen clubs, and he too expressed his clear preference for Oase. Granted, my personal bias probably played a role in swaying his opinion. For him, he really liked the Oase relax room that is off-limits to the girls. He was disappointed about the other clubs not having an off-limits relax area.