If the bubbles are ontop of lr that has algea or detrius buildup(usually stagnent areas) then its mostlikely the start of cyano bacteria(this can be reasured by testing water impurity levels).
If bubbles are sparangly and scatered through-out the tank and your water levels are fine .don't worry about it.. micro-bubbles are harmless, unless organisms are living in a bubble dominated tank..(like the inside of a protein skimmer chamber).
I don't see much negatives if bubbles are on liverock, however u don't want bubbles to take host in inverts or coral's flesh, sincce it may suffocate them and create embolisms in the flesh....
That said, micro-bubbles on occasions are fine, many of which are due to the association of zooplankton and the transient population associated with braking waves(air flow)..Generally micro-bubbles are generated as a volumetric source by biological organisms, air flow rate, upweling of bottom water, water changes , replenisments of evporated wate, protein skimmer incorrectly set-up,plumbling air leaks ect.....
Small bubbles are very common in tumultuous reef environments, and areas where waves break are often dense with both reef life and small bubbles. In addition, in tanks and on reefs, many bubbles of various sizes, including true "microbubbles" are produced by photosynthesis, and this is especially the case in highly illuminated environments. In my own tank, a constant rise of bubbles, especially in the afternoon, are produced by various corals and algae in even some of my less-illuminated systems. Larger bubbles frequently get sucked into pump intakes, and are chopped up to even smaller sizes and distributed throughout the tank. I won't even start to discuss the massive numbers of bubbles produced by various surge devices. These water motion devices have great benefits in aquaria, and even as anecdotal aquarium observations, I have never seen anything disturbed, irritated, or harmed by the rush of bubbles.
In the natural ocean the bubble population significantly influence the scattering process in the ocean, especially in oligotrophic waters, bubbles are a large contributor to the missing terms in constructing the observed backscattering coeficcient of the oceans..
You decide if bubbles are good/bad or ugly...