Pre-sets are always a great starting point to see what a vst can do.  From there on, tweaking is a avenue to travel.  Some pre-sets stand  on their own while some need embellishment.  Either way, I look forward to a vst having pre-sets to get an idea what the creator had in mind and even suggested uses.

I guess it really depends on which type of plugin we're talking about. For something like EQ or a limiter, I never use presets.  Compressors, distortion, reverbs, delays, etc, I often dial in myself, but I'll sometimes start with a preset and tweak it to fit my needs.  For instruments, it can range from straight presets (esp. with something like a piano, string, or other sampled "real" instruments) to tweaked presets, to sounds made completely from scratch (esp. VA synths).  I do enjoy sound design, so that usually means creating my own sounds or heavy tweaking of presets, but I'm certainly not above using a straight preset when it fits the need.

I answered this in the other thread but I'd like to toss out a recommendation.
 
The Pro Channel presets for Gibson acoustic guitars can be amazing. Right now I'm working with a guy that has what could be described as a Gibson museum. At any time we have 20-30 vintage acoustics at hand. If I get stuck on the EQ or want to quickly audition different sounds, they are the bomb.
 
When you are recording 7 or 8 different guitars per day, using the same set of microphones, EQ is real important for capturing their unique character. The Pro Channel EQ is my favourite for these old guitars and the Gibson presets are my go to starting point.

I use presets for things like chorus and tremolo, stuff like that.

All of the above

It really all depends. I find things like reverbs, I put in parallel and use presets, EQs I only adjust HP,LP points. Amp Sims, I start with a preset then make tweak. I have grown found of throwing efxs into  fx chains then creating some knobs which means I tweak after the chain is created but only a few parameters. I use neutron a lot and that is pure preset though I may have a band pass in front of it. 

Inveterate preset tweaker here. That said, I'll happily and unashamedly use a preset exactly as it is if it happens to work perfectly well for the purpose exactly as it is. That's hardly ever the case, but when it is, I have absolutely no issue with using a preset as it is. I'm a musician first and foremost, and I'm not precious about being a sound designer as well; I can do that up to a point, but I suspect the people who make their livings doing deep sound design are better at it than I am, just as I'm probably a better player than many of them since that's my main focus in life. So I'm happy to focus on the parts I do best and tweak where needed. Of course composition and sound design are tightly intertwined at this point, at least for me, so almost invariably some special sauce is needed. Also, I'll sometimes use a preset as it is but mangle it into something very different with FX - maybe also using a preset or a tweaked one... but I see the value and creativity in what I do as being far more about combining elements into a new thing, than needind to start from scratch for purist reasons, though that should not be construed as a judgment about someone else for whom that does seem essential. 
 
I'm also a big fan of randomization and/or morph functions, just clicking away until something grabs my ear and then tweaking from there as opposed to from a preset. Again, what may seem lazy to someone else seems to me to be a creative act - applying my specific ears and tastes to turn something random into music. It's not what you do, it's the way that you do it... 

When it comes to guitar presets they are usually tailored to other people guitars so you need to tweak them. I guess the vast library of own presets is a sign of maturity.
 

Hi. As most of the others, I sometimes start from a preset and tweak from there.
But mostly I have made presets that suits my different singing styles, certain guitar tones, a particular drum kit etc. They usually only need minor tweaks.
I also will use a preset if it fits. I will then save it under another name / preset for later reference.
All the best.

So yes I use them, yes I create them and yes I tweak them. I had hoped to be able to apply them to many sessions but discovered each song requires its own settings. Sometimes i get lucky and can use a preset and modify it so I often start with one. I also have some fx busses I built presets around to sidechain vocals to.