Of course there is no scam in registering IDN subdomains with centralnic. The scam is when you try to falsely establish demand, and thus value, for said domains by stating that you've had high offers for them (thus fishing for real offers so you can unload these worthless domains). I don't think I'm the only one here that simply does not believe that you have had any real offers on these subdomains.
Regardless of that, I would like to tell you something about IDN subdomains. While this may not apply to Chinese yet as far as I know, it does apply to Japanese. Earlier last year, Yahoo.co.jp (the dominant search engine in Japan) was giving incredibly high rankings to Japanese IDNs. As most of the good Japanese IDNs were already bought, Japanese webmasters started creating Japanese IDN subdomains by the thousands in order to gain rankings. In a matter of several weeks, they pushed nearly everybody out of the first page in the SERPs. Due to this, Yahoo Japan changed their algorithm and actually, as most people believe, penalized IDN domains and subdomains. The domains and subdomains which previously ranked on page 1 sank to page 85 or something. Additionally, many of the domains and subdomains were simply removed from the results (de-indexed).
IDN subdomains like yours won't get any type-in traffic, and if Baidu (the dominant search engine in China) take a similar approach as Yahoo (might be that they have already done so) they they wont rank in the SERPs either. If a domain doesn't get type-in and can't rank in SERPs, then what good is it?
Just something to consider when you are pulling out your credit card next time.
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