Notably they use the scripture about he who is faithful in least is also faithful in most. This means that the one who goes along with the white dress shirt, wears that suit coat in 100 degree weather in service, puts in every possible yoctosecond in service, listens only to the 225 pieces of s***, and would not even look at a strip club or porn shop is the one that is going to be faithful in most. What they don't say here is that this resembles the pharisee who scrupulously strains out a gnat but will gulp down the camel.
Practically, why would someone who wears that suit coat when it's very hot be a better servant later? This is the person that is most likely to end up dead of heat stroke. And what good is it going to do then? And if they are screeching around at 160 MPH to make the most out of service, what good will it do if they have an accident and kill 50 or 60 innocent people while racing to the door? And aren't many of the pedophiles in the organization scrupulous about the music they listen to or the white dress shirt? Are they faithful in much?
And who gives a &$&^ about being faithful in "much"? Most of the "crimes" are victimless. Doing fornication with a consenting partner is not inherently wrong. True, it has consequences that may be unpleasant. Smoking is not inherently wicked (it is stupid, since it will cost you much and give no benefits; however, that doesn't make it wicked). Drunkenness, however stupid it may be, is not wicked. Nor is it wicked to commit idolatry (and in many cases it isn't even stupid. Idolatry is not stupid if you get more benefit, or create more value, in doing so than it costs you). For sure, celebrating Christmas is not wrong whether you believe in it or not.
The only thing that is truly wicked is any act that you intentionally and volitionally do that uses initiatory force, threat of force, or fraud against another person or their property. Doing that is truly wicked--and that goes for the initiatory fraud that the Witlesses' leaders use to hound people into doing ever more. Any act that doesn't involve using initiatory force, threat of force, or fraud, though it may be stupid, is not inherently wicked. And that holds true for a minor "sin" like listening to rock or disco music, or a major one like idolatry or fornication.