Can DeoxIT® GOLD build up on RCA plugs?

I use DeoxIT® GOLD to clean my stereo set and interconnect RCA's. After cleaning, there seems to be a small amount of DeoxIT® GOLD build up on the RCA plug surface, and it seems to be degrading the sound. How can I remove the build up?
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The "build up" you're referencing is actually dissolved oxidation. The surface may have needed a cleaning with DeoxIT® contact cleaner PRIOR to treating with DeoxIT® GOLD.

If the buildup is greenish, that's copper (bronze, brass) oxides. If the buildup is more black, that's nickel (silver, tin) oxides.

Using DeoxIT® contact cleaner in the 5% spray (#D5S-6) should remove those contaminants.

In this case:
1. Unplug your system prior to any maintenance;
2 Apply 99% IPA (alcohol), and alllow the surface to dry thoroughly;
3 Apply DeoxIT®, and wipe away whatever contaminants are lifted from the surface with a clean, lint-free cloth.
4. Use "canned" (compressed) air, if necessary to remove surface contaminants.
5. Finish with the DeoxIT® GOLD AND maintain thereafter with DeoxIT® GOLD.

NOTE:
DeoxIT® GOLD (formerly ProGold)
DeoxIT® SHIELD (formerly PreservIT)
DeoxIT® FaderLube (formerly CaiLube MCL)
DeoxIT® Grease Type M260 & L260 Paste (formerly CaiLube Grease).