Real Oviedo - Barcelona...
It is a very easy game for Hansi Flick's students on paper. However Real Oviedo haven't conceded too many goals at home. They have conceded most of their goals away.
But as a reminder, they faced Real Madrid home already and lost by 0-3.

I expect Barcelona to do a similar work against them.
-1.5 handicap on Barcelona @1.66 seems really nice.
Let's just look at the overall strength of both teams, and I think there's a significant difference between Real Oviedo and Barcelona. Barring any major upsets, Barcelona should easily win this match.
A handicap of -1.5 with odds of 1.66 is certainly worth betting on. Barcelona currently has a very strong team, and it's highly likely they'll win by more than 2 goals.