It could just be user error. The plastic didn't seem to react to the liquid glue as well as the Dragon and Tamiya kits, too.
But, I think the moulding is not quite as crisp and precise as the Tamiya. Still much, much better than the Dragon.

After a bit of a pause I've made a bit more progress on the builds.

First, the Hobby Boss kit;

I added a black box in the main wheel well that was missing but was on the Tamiya and Dragon kits.
I added yellow electrical cabling in the main wheel well, in part to draw the eye away from the slightly rough areas where the cockpit mounting tabs were removed. This was much harder than I anticipated and looks a bit messy. I was going to do the same on the other two jets, but decided it was more effort than it was worth.
I added both elevator and aileron control rods. These are small things, but it is curious that none of the kits have them (although the Dragon kit does have the aileron rod).
The internal armoured windscreen is too long and sits a bit too high. I added a thin bit of plastic card, as you can see in the pictures, to lower it a bit.
Curiously, Hobby Boss molds the gunsight in solid grey plastic. As the aircraft I'm modelling had it's gun removed, I reasoned that the gunsight would have been removed as well. On the real aircraft, this slots into a tube mounted above the instrument panel, and the gunsight may be dismounted to improve the forward view for landing. So, I mounted the gunsight and cut it off just in front of the instrument panel.
I replaced the lost seatbelt.
I added some plastic card as this aircraft had the deeper rudder trim tab.
The wings fit quite well to the fuselage with a few small gaps requiring filler here and there. The fit is not quite flush underneath the fuselage, but the fuel tanks were designed to be dropped out of the fuselage so the fit of these panels were probably a little rough anyway.
I cut the solid wing tip formation lights off and will replace them with shaped clear sprue later.
I painted the inside of the camera ports with clear smoke to hide the non-representative interior without making the windows look solid.

6 attached images. Click to enlarge.

And the Dragon kit;

I've made a bit of progress on the cockpit but haven't attached the wings yet.
I'll post photos when I have.

Really good progress, Michael.
A 262 is still on my wish list, so I will follow your triple build and see which suites best for me.

And so to the Dragon kit:

The pilot seat comes in two parts with the seat pan having a molded in seat cushion. However, the pilot would have had a seat parachute that fitted in the seat pan, so I ground the cushion out using my mini drill.

1 attached image. Click to enlarge.

Another problem I discovered was with the slots for the horizontal tails. These are off centre, leading to the tails sitting too high. So, I trimmed the lower edge of the slots down and packed the top of the tail tabs with slivers of sprue. Then the tails fit very neatly, without any steps to the fuselage fairings.

2 attached images. Click to enlarge.

Seems like it is giving you a good fight! Very nice solutions to the different challenges Michael (@michaelt)