Alright, this thread is old as crap but I figured I'd throw in my two cents since this is still on the front page and I assume everyone else with this problem is coming here to look for an answer.
I have a "definitive guide" to amp sims available on Reddit but it's really long and i'll condense it here, there are a lot of possible reasons why your patch "sounds like lollipop" but I'll list the most common reasons:
1) Poor gain staging. The line 6 manual says -36 to -12 is the optimal level for the sim, so make sure your peak is around -12.
2) Not using a DI Box. The scarlett is a great cheap interface to be sure, but Hi-Z's suck. Literally all of them, even on extremely high dollar interfaces. Don't rush out and buy a cheap DI Box though, you need one of good quality. The Countryman Type 85 and the Radials are a good choice, and used they run about 100 bucks. A bad Hi-Z, which again is all of them, can make your tone extremely muffled or extremely thin (kinda depends on the interface and how bad the Hi-Z is)
3) Not having a properly set up guitar or turning away from noise sources. If your guitar is set up like crap, out of tune, and/or your guitar player sucks there is literally nothing an amp sim or impulse response can do to remedy that. It's not a miracle worker. Also with passive pickups you need to make sure you turn away from your computer/tv/monitors/ect and on every guitar mute your strings with foam/tape/whatever after the nut and before the bridge (if applicable)
4) Dial in your tone at an optimal level: First off, don't try to dial in a tone while you're playing the guitar. Your ears are going to trick you. Record something short and sweet, loop it, and dial in the tone. Also don't fall into the "bedroom tone" trap and try to dial in a tone at a low volume. You need to be bumping, at least 80dBSPL (google fletcher-munson curve for info). If this is not possible for you over studio monitors, use a good pair of studio headphones with a good frequency response.
Now if you're doing those 4 things properly then you've entered "Personal Taste Territory". No one can help you get "your tone" but you, but I do have some simple advice.
1) select your amp/cab and set all the controls on the amp to noon. No tube screamers or fancy crap here, just amp and cab.
2) play. Does it sound like lollipop?
if yes: Change the cab
if still yes: Change the cab
if STILL yes: change the amp head
3) once you found a combo that sounds the best to you in it's "neutral" state then add your pedals and start your tweaks but keep a few things in mind here:
#1 An Amp sim does not replicate what an amp/cab sounds like if you're sitting next to it. It emulates what amp/cab sounds like AS CAPTURED BY A MICROPHONE. Therefore if you don't really have much experience recording real amplifiers you might not even be aware of what they're supposed to sound like with no studio magic or mix to support it.
#2 Your "mono" tone is different than your double tracked/quad tracked "panned tone". You will lose a little high end and low end, so if in mono it sounds a little boomy or harsh, it's OK.
#3 Too much gain on amp sims is bad
#4 Too much gain on amp sims is bad
#5 Too much gain on amp sims is bad
#6 Too much gain on amp sims is bad
#7 Too much gain on amp sims is bad
#8 Also, if you weren't aware: too much gain on amp sims is bad. Use AS LITTLE GAIN AS YOU CAN GET AWAY WITH. You want the gain set to where you really have to work for the distortion. The tall-tell signs of too much gain: zero note dynamics, really obnoxious harsh high end, you pick softly and it sounds like a slayer album. The fizz is your best friend when determining too much gain, pay attention to what it's telling you. In my experience this is where 90% of amp sim users FAIL miserably.
The helix is just as good as any other amp sim in the head department, the cabs. EH, they're usable but not great. You can get a usable tone without 3rd party impulses, but if you're ultra-super-picky then i suggest using impulse responses but this kinda defeats the purpose of Helix native because you can get equal quality heads for free or much cheaper.
Finally, you'll never get the tones you hear in demo videos. You aren't them and you don't have their gear or their picking hand. "Tone is in the hands" is a real thing mate, sure you can do what Glenn Fricker did and try to disprove this by cranking the gain up to 8 and boosting it with a tube screamer so literally a piano would sound the same out of that amp but trust me: don't fall for demo tones. Always try before you buy.
Hopefully this has helped someone, if not feel free to PM me. I do reamps professionally and own basically every amp sim (besides helix ironically because the trial didn't impress me and the authentication system is terrible) and they all are usable. Even Bias FX/Amp........ but I won't go on a rant about positive grid.
Addition:
One final thing I'll mention is: Yes, dual amp/cabs or dual micing IS a thing but i recommend avoiding this unless you're experienced. With a sim, or even in real life, a 57 in the sweet spot (on or off axis, whatever tickles your fancy) WILL give you a good sound so just stick with a single amp/cab/mic until you can get "good tones" with them before you jump down that rabbit hole.