Apparently Klingons, or at least Worf, hate to bathe. Does this mean that Worf stinks to high heaven? Or do Klingons consider using the sonic shower/washing at the sink to be acceptable, whereas literal bathing in a tub is not?
Klingons do appear to possess an odour that some humans and aliens find offensive.
In DS9: Trials and Tribble-ations, Darvin (unaware that Worf is Klingon) describes them as:
Bashir and O'Brien defend him by reassuring him that he doesn't smell bad:
O'BRIEN : Don't take it personally, Worf.
BASHIR : I rather like the way you smell.
O'BRIEN : Kind of a... peaty, earthy aroma.
BASHIR : With just a touch of lilac.
Soren certainly seems to finds lursa's breath quite unpleasant in 'Generations'
The novelisation describes it in more detail :
The aging ship groaned and shuddered unceasingly -- and stunk of warm, wet animal, making him long for the pristine, silent corridors of the Enterprise...Klingons turning to regard him, his upper lip twitched faintly. They smelled the same as the ship; and though Soran had always believed himself an unprejudiced man, this particular species tested his limits.
In Voyager : Prophecy, again they're described as having an earthy musk.
NEELIX: Well, I've been studying the Klingon database. They're a fascinating people, very robust. And they certainly seem to appreciate my culinary skills.
JANEWAY: Looks like everything's running smoothly.
NEELIX: Ah, not quite everything. some of the Starfleet people have been complaining about the smell. Personally, I find it appealing. A kind of a musky aroma.
JANEWAY: Maybe we can adjust the environmental controls to filter out the musk.
Yeoman Burke also thinks they smell bad in 'The Undiscovered Country'
CREWMAN #1: They all look alike.
CREWMAN #2: What about that smell? You know only the top of the line models can even talk and...
Their ships are also pretty unpleasant smelling, at least according to McCoy in 'The Voyage Home'
McCOY: You'd think they could at least send a ship. It's bad enough to be court marshalled and spend the rest of our lives mining borite, ...but to go home in this Klingon flea trap...
KIRK: We could learn a thing or two from this flea trap. It's got a cloaking device that cost us a lot.
McCOY: I just wish we could cloak the stench.
We have known from the very first season that Worf hates baths. In Conspiracy, there is an exchange of dialogue that goes as such:
TROI: Data, it's just not the same. Have you ever been for a real moonlight swim?
DATA: One can swim in moonlight?
TROI: How about you, Mister Worf?
WORF: Swimming is too much like... bathing.
So we can infer from this line of dialogue that yes, Worf does stink.