One of the generally accepted ideas when buying optical media is: you get what you pay for. There are different "grades" of media that are sold to (or manufactured for) different brands, and the highest quality discs are mostly only for well-known brands as these are also priced higher by the manufacturer.
The "thinness" or translucency of the disc may be a visual cue that the disc may have low reflectivity and may give players/drives a hard time reading it, but this is not always the case. I would prefer opaque discs than transparent ones, but it might just be a matter of taste and not a qualifier of absolute reflectivity.
If it burns well, reads well, has good longevity and fits your purposes for the media, then the transparency of a CD shouldn't be a problem. If it is cheaper - well it's a good buy then. I also have Daxon media of differing brands - from Verbatim, no-name, and even BenQ - and while even the Verbatim (a good brand) is slightly transparent I have never had any problems with it. There are some reports of Daxon media "peeling", but there are not enough instances of it happening for it to be representative of the whole Daxon CD-R line.