The negatives seem fine, but I'm not really sure what I'm looking for.
What you'd be looking for is very faint images on the negatives. In a proper exposure, they should be crisp and nicely contrasted on the negative. As in, the whites should almost be opaque or very dark (negative), and the blacks almost clear. If, however, everything is just varying shades of almost-transparent, then it means the negative was underexposed, and there isn't much data available to work with. So no matter how they develop it, it's gonna look drab and cloudy like the ones in the OP.
Whereas if the negatives are crisp and contrasty and fine, yet you get milky crap results, then CVS screwed up, not you.
Therefore, you can distinguish between developer error versus photographer error by looking at negatives. Either could potentially lead to the above results (the color cast can also result from the same issue -- if they have to dramatically alter the timing of the development to adjust for a huge missed exposure, then the colors will end up odd due to the strained procedure. OR they could have just effed up.)