My main ADV is from Tasty Vapor and their bottles have these needle tips, really thin pointy jobs. Tilting the T3 and I run the
juice directly on the inside wall of the T3, haven't had a problem (yet, watch me fill the mouthpiece today

) I also underfill the T3s a bit, so the
juice doesn't come all the way to the top of the center post... I *have* done that and bobbed some
juice in there just b/c it was too full.
I wish I had some carto condoms-- all my cartos were EMDCCs and they didn't come with them. But they seem handy! I use a paper towel/something underneath instead.