So what does the term "Uncleanness" encompass? Well? the context makes the idea pretty clear, but what does that mean exactly, in modern life? It is up to the interpreter of the verse to say, to give his own opinion...and that is exactly what the WT is doing when they refer to a broad term "pornography". At its worst porn is vile and illegal, but softer stuff has varying degrees of badness and at the low end of the scale, who can say that they have not indulged?
I am no scholar but I believe that the way they diced and sliced up the words of Eph 5, 3 - 6 is deliberately confusing. The paragraph reads
""The wrath of God is coming" upon all who unrepentantly engage in such practices as fornication, obscene jesting,and "uncleanness of every sort " which would encompass the persistent viewing of pornography"
The NWT of Eph 5 .3-6 reads
"3 Let fornication and uncleanness of every sort or greediness not even be mentioned among YOU, just as it befits holy people; 4 neither shameful conduct nor foolish talking nor obscene jesting, things which are not becoming, but rather the giving of thanks. 5 For YOU know this, recognizing it for yourselves, that no fornicator or unclean person or greedy person—which means being an idolater—has any inheritance in the kingdom of the Christ and of God.
6 Let no man deceive YOU with empty words, for because of the aforesaid things the wrath of God is coming upon the sons of disobedience. "
If I read that with an open mind, it tells me that uncleanness is among the things that should not mentioned among the Christian congregation (presumably in a "smutty" way). But does that mean that telling dirty jokes and looking at rude pics has the same gravity in Gods eyes as fornication and adultery?
If we read it that way, it is a human judgement not the clear word of God.
{NB I am not defending pornography, just trying to get a sense of perspective]