The analogy of the wedding garment is from Scripture, where Christ explains that you either have one or not. Those that don't have one, cannot stay at the wedding feast (i.e. salvation) and are "cast out into the darkness" (i.e. hell).
The analogy never includes clean vs dirty.
I agree. In Jesus's quotes, he speaks of having a wedding garment or not. But in the Apocalypse, St. John speaks of washing the robes. Here is a quote from Chapter 22:
14 Blessed are they that
wash their robes in the blood of the Lamb: that they may have a right to the tree of life, and may enter in by the gates into the city.
15 Without are dogs, and sorcerers, and unchaste, and murderers, and servers of idols, and every one that loveth and maketh a lie.
And and speaking of the 144,000 in chapter 6, St. John says:
13 And one of the ancients answered, and said to me: These that are clothed in white robes, who are they? and whence came they?
14 And I said to him: My Lord, thou knowest. And he said to me: These are they who are come out of great tribulation, and
have washed their robes, and have made them white in the blood of the Lamb.
15 Therefore they are before the throne of God, and they serve him day and night in his temple: and he, that sitteth on the throne, shall dwell over them.
16 They shall no more hunger nor thirst, neither shall the sun fall on them, nor any heat.
17 For the Lamb, which is in the midst of the throne, shall rule them, and shall lead them to the fountains of the waters of life, and God shall wipe away all tears from their eyes.
So I think the two interpretations are not far off. But I think that a baptized soul in a state of grace is in the same situation of cleanness as a justified soul in a state of grace. Both the baptized soul and the justified soul (BoD) are clean at the moment of regeneration but can lose their state of grace. The difference is that the baptized soul is likely to be more vigilant and can more easily recover from his fall. The merely justified soul, after falling a few times, will probably not be able to persevere to the end.