Let's look at incredible 8 goals we've scored.
1 was offside. - Yes, but after a nice pass from Rakitić and great movement inside penalty box from Messi. So while it was offside it was a nice build up goal.
1 was due to pure luck. - A bit of luck but a good counterattacking move from Paco
1 was due to actual good passing and link up play.
1 was off a corner. - Corners are part of the game and we struggled to score from corners over the last two seasons (we were actually quite good in that regard in Lucho's first season). So I will take that and think we'll improve from corners with no Neymar to take them.
1 was in the 90th minute after the opposing team had abandoned their shape and the game was dead. - So that goal shouldn't count because it was scored in the 90th minute or what? It was also a beatiful action and nice through pass from often criticised Gomes (which will give him confidence) to Dembele, who got his first assist (again confidence boost for him) and Suarez with a good finish, that will have a positive influence on him as well. It was also a manita goal against our rivals and those goals are always important.
3 were due to brilliance from Messi. - You can call it Messi brilliance if you want but: 1st goal against Betis - good cross from Deulofeu
1st goal vs Alaves - Iniesta through pass and Alba cross to Messi, a bit lucky with finish but still a nice goal
Oh, and you forgot Roberto goal vs Betis which was again made by good assist from Deulofeu so we actually scored 9 goals in La Liga so far.
Yes we have scored 8 goals but this style of play is not sustainable at all, I'm sure once we collapse in the middle of the season after our luck dries up just like in 15/16 you'll be the first one to make excuses.