ive had plants that touch leaves and you do get a watery substance, but on one occasion i did get sticky shit where the leaves were touching, it had a strong odour aswell. you need to find out what your humidity is. mine got like that when i was first growing and i stuck the plants in the bottom of a clothes cupboard, so the air will have een really dry, i think if you dont have bugs then thats where your problem lies, if the other guys arent seeing that sticky stuff and just watery shit, its because they have there r/h sorted.
just my 2c worth.
also i wiped my sticky shit off, bbut if you left yours and the lights got too it then thats how it turned a bit spunky looking.