"Thought the whole point was to strongly flavour the bait."
or to boost the "food signal" of the bait - fish oil, csl, liquid liver, meat extracts, etc, etc. you cant overload them unlike some of the flavours...
If you use natural ingredients in your glug. Like the ones mentioned above by Frothy then you can not use to much. If using manmade flavours then you have to be sparing but these are not really recomended for glugging baits.
Not sure if anyone's covered this one, but I make my own boilies using sardines and cheap canned tuna (in brine) with a couple of eggs whisked in (Angler's Mail covered the full recipe a couple of weeks ago). As an added boost, I make a glug out of supermarket oyster sauce (thick and gloopy) thinned slightly with Thai fish sauce (runny). The baits can remain in the glug in an airtight jar for months (still got some I glugged last August). The glug itself is more or less a natural product and not overpowering to carp or barbel.
Tim,
As long as you like mate - just make sure the container is airtight and kept in a cool dark place (a bait fridge is ideal).