Colored caps generally mean the juice is Dakang, and chinese juice producer. The color of the cap itself I don't think means anything. Dakang juice is known for always having an orange-yellow tint, even unflavored, due to their extraction process to get nic from tobacco. There is also a particular taste to their juices, independent of any flavoring they add. Some have no problems with it, love it, and buy it in bulk. Some, however, do not like it...I am in that camp, and not just from the flavor/color, but also they are PG juices, and I don't like PG's affect on me.
The juices should be "fine", meaning they are not unsafe to vape. Whether you like them or not is another issue entirely. Lots of great juices from other vendors out there, and not Dakang in origin, with many being made very well in the US. MyFreedomSmokes offers outstanding juices for excellent prices, and no base coloration or underlying taste.
If you are like me, however, and get tired of PG, or hit or miss flavored juices, you may consider going purely DIY. Cheaper and with some experimentation you get exactly what you want every time.
Also, RY4 is a caramel tobacco flavor, so should be deeply colored regardless of the base that is used.
