I have stainless steel ball valves on my FVs, they are easy to clean in situ with a small bottle brush, and also easy to remove, clean and replace.
I have never really understood why people discourage the use of taps by posting pictures of dismantled mouldy taps, if you can take it apart to take a photo of mould, then you can also take it apart to clean it, so they're just advertising their poor sanitation regime.
Removing the lid of an FV and dunking a turkey baster, ladle or hydrometer into your FV is also not a risk free method. I would suspect that many of the infection and pellicle threads on homebrew forums would prove this point, particularly from new brewers, keen to monitor their brews. Horses for courses, but you're unlikely to get any airborne contaminants entering your FV via a tap.
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