After installing the latest Wine release, which currently is 2.0 (I chose the development branch) on XQuartz 2.7.11, I was having problems with blurry text in both winecfg, regedit and other programs launched through Wine. After trying to enable font smoothing and font replacements (source) with only slight changes I found someone trying to solve the same issues (source), albeit compiling everything from scratch which I don't want to do. It turns out that the Retina display on my MacBook Pro was causing the issues with blurry fonts because Wine was not using the "real" resolution, only the reported "lower resolution".
To enable Retina support in Wine open the registry editor via a terminal, preferably through Wine Devel.app installed with Wine:
$ wine regedit
Then find the folder/key: