To me I don't feel that people are looking down on Arsenal just that due to previous seasons that people trusted Arsenal to a certain stage and they started flopping and losing out. Arsenal tried to play draw with Bayern Munich but we all saw that Arsenal could have won had it been they added more effort in the game but however, Arsenal performance recently is convincible because they have maintained a good form for a long time now so they are expected to win a trophy this season if they maintain in this impressive display.
Actually it's going to be difficult to just trust Arsenal with the chance of winning as other top teams like Liverpool and Manchester city are in very close proximity with them with regards to their points so far, their was actually the similar case last season just as you have rightly mentioned, Manchester city were able to get ahead of Arsenal who were at the top of the able few weeks to the end of the league.
That alone made has made so many have a reason to not trust Arsenal enough because they were in almost similar form as they are currently last season, so it's very possible they may not be able to maintain this position they are currently till the rest part of the season as there's only but few weeks to the end of the season. Manchester city and Liverpool has still got what looks like a possible opportunity to winning the trophy too this season, importantly Manchester city has got the trophy to defend as defending champions while Liverpool want to make sure they are able to get to win this lats time before their head coach leaves.
Sadly for Liverpool they lost their Europa game, one of their hopes of getting a trophy This season and that could actually affect their mind and their confidence but then i think since they seem to be seeing better opportunity with the premier league they may want to utilize it well enough to get to win the that trophy and see to the fact that This season they are able to end the season winning something.