Lesson No 2: When he's in this marauding mood, Bernard Brogan is a class apart, period.
Lesson No 3: Jack McCaffrey may one day belong in the same elevated company, and sooner than we think.
Now for the obligatory caveats. One, Louth were every bit if not more experimental than Dublin. Two, the Louth defence played as if it was still Christmas week - either full of turkey or full of festive generosity or both.
And three, Sky Blue supremacy was so absolute that they were able to create chances virtually every time they attacked, finding the space to amass 4-15 while clocking up the wides (14) with abandon too.
It was a January jaunt, a winter cruise, call it what you will. Next up, Kildare in the final at Parnell Park on Saturday night (throw-in 7pm). We'll hazard a safe guess that this will offer a more accurate barometer of Dublin's early progress under Jim Gavin.
A week earlier, for the dead-rubber against Wicklow, Gavin had picked a team replete with so-called fringe players and suffered his first defeat with the Dubs.
Here, his more balanced blend of marquee names and aspiring future stars proved a much more prolific concoction, reflected in a 17-point chasm (4-15 to 0-10) at the final whistle. Now, even with the first cup of his tenure within reach, Gavin insisted his attitude towards the O'Byrne Cup won't change - namely it's a worthwhile pre-season tournament designed to find out which players are worth sticking with.
"No disrespect to the tournament, its concept is fantastic, supporting players who have gone through hard times, and we fully endorse it and hopefully we'll get a big crowd in Parnell Park next weekend," he explained.
"It's a chance for managers to give players game-time in a meaningful competition . . . as I said, there's a bigger agenda with this squad."
So then, will whittling down his National League panel be a fraught process? "No, it's pretty black and white," Gavin maintained. "It's the guys who are performing who get the slots, and the guys who aren't go back to their clubs."
One player who won't be taking the latter route is Bernard Brogan. Of the established stars on view, the former Footballer of the Year arguably has most to prove to the new boss after his topsy-turvy 2012. Ironically one of his best days last year came against Louth, when he scored 2-5 (2-4 from play) during a Leinster quarter-final romp.
Here Brogan went further, scoring 2-7; he was also fouled for one of his six converted frees and laid on the final pass for another 1-3.
From the get-go he was in the mood to wreak havoc and two goals in the space of 60 seconds (in the ninth and 10th minutes) confirmed as much. Already it was a case of by how much, and after Brogan pointed his own free soon after, Louth manager Aidan O'Rourke felt compelled to switch Jamie Carr from this poisoned marking chalice.
As the half proceeded, we saw occasional flickers of Louth resistance up front (coming from Jim McEneaney and David Reid) and far more examples of Louth disarray at the back. Even on soft ground, McCaffrey's gliding quality as an auxiliary attacker stood out. One such jet-heeled burst led to an early point; then he was involved in the build-up to a Paddy Quinn point; and then on 22 minutes another McCaffrey shot rebounded off an upright only for Louth 'keeper Seán Connor to cough up possession and, to crown his misery, Emmett ó Conghaile's attempted point dropped over his head but under the bar.
Goal number four arrived in first half injury-time. Throughout the half, Diarmuid Connolly had capitalised on Louth's lax marking with a string-pulling performance on the '40'. Now he found Paddy Andrews, who skinned Bernard Mulligan and crossed for Brogan; his clever flicked pass left Paul Hudson with the simplest of fisted goals.
At 4-8 to 0-7, there could be no way back for Louth. At least their second-half defending was more tenacious - it could scarcely be less - but the flip side was a toothless forward display comprising two wides and just three points, none beyond the 48th minute.
For Dublin, even as they eased off the gas, Denis Bastick continued to be the dominant midfielder and we had a lively late debut cameo, capped by a point, from minor graduate Cormac Costello.
His dad looked pleased. His son knows there'll be far tougher challenges ahead.