Guinea pigs have a milky white eye cleaning fluid. Seeing drops of that that have not been absorbed again by the tear ducts is no problem.
Watery fluid however mean that there is an irritation or potentially an eye injury like scratch, something stuck under the eyelid or minor hay poke to the eye, especially if it continues, if the eye is squinting and pulled in somewhat. The sooner you see a vet in these cases, the better for a quick and smooth recovery. Eye injuries and infections can deteriorate very quickly and the extent of the damage may not be visible to the naked eye, especially if it covered by a film of tear fluid. Vets use a special dye and ultraviolet light to assess any potential damage.
The watery fluids tries transparent. Often it can mean that just a spec of dust or a hair has been washed out as a one-off but do not treat it lightly in case it is something more serious.
Yellowish, orange or green thick mucussy crusts on the eyes and nose mean an advanced untreated URI. this always needs to be seen by a vet for a diagnosis and an antibiotic.