Arsenal striker Robin Van Persie was involved in a spitting row with Bolton's Matt Taylor at the end of yesterday's 2-1 defeat.
Arsenal denied claims the striker spat at his opponent after TV footage of the confrontation, says The Sun.
The Gunners looked at the incident and a spokesman said he was merely spitting on the ground.
Wenger, who had not seen the incident, cited defensive frailties and conceding six goals in their last three games with draws against Liverpool and Spurs before this defeat.
He added: "It is all very frustrating but that has been the story of our season.
"This week we could've taken nine points, we've taken two."
