@acrylian:
OK, I've done some more testing:
I installed a new copy of Zen on another hosting, just for test purposes. Set `$conf['UTF-8'] = true;` as in the other case.
In front-end and in the MySQL database all is OK, all characters are normally readable.
Now, where should I look for the problem, then?
If I see `< ??? ??? ??? >` instead of normal letters in the MySQL database in the first case, does this mean that the 'SET NAMES' trick is not working there, for some reason?
Is it possible that some other server configuration is interfering with it?
I always thought that SET NAMES if specified in the application (right around the code where the connection to the database happens) is having the top priority and the encoding should be as defined there, even if globally on the server the default MySQL encoding is latin-1 or some other?... Or am I wrong?
I'm just looking for clues, as currently I can't use the Zen when MySQL data is unreadble...

(well, front end is OK, but having '???????' in the database will lead to trouble one day or the other...)