I think there are a lot of relevant points above, but to expand upon some things from requiemmorrow and TAG Manager: no matter how fluent you might be with Japanese culture and language (and one does not necessarily equal the other), your presence in society at large and especially in the world of adult services is almost always going to be tolerated rather than appreciated.
I don't patronize soaplands, more of a delivery/hotel health person, but even in places where I have zero difficulties with communication and am friendly with the staff, there is always an unspoken understanding that my privileges are given because I am respectful to store staff and providers, well-behaved, and I recognize that those privileges could be revoked at any moment. There are shops that I used previously and they no longer accept foreign clientele; if I drop in, they don't tell me to leave, they just calmly explain that they do not have girls willing to service me that day. (So, politely telling me to leave.) In soaplands, where you can be physically seen by other patrons, it's not necessarily great for business. Unless a shop is actively pursuing non-Japanese customers (at a premium, natch), I get the impression that they don't want to upset their majority Japanese clientele.
As long as you are visibly or audibly foreign (and don't deceive yourself, no matter what you might think, your accent will almost always betray you), there's a glass ceiling in terms of how you are treated and it always goes back to your non-Japanese status. Weird personality? Physical impairment? It's obviously because you are not Japanese, no other possible reason. So, yeah, learning the language can be very helpful, especially with the providers themselves, but it's no panacea given the overall structure of the fuzoku industry.