<human>: Could you distill the essence of the text into 1-3 sentences?

Hello reddit. Made a throwaway. So my boyfriend(22M), of 3 on and off years with me (20F), has quit smoking for about 10 months now. However when he goes to work every here and there when I kiss him I can taste tobacco in his mouth. He has friends at work who heavily smoke and who he hangs around with. And when I question him he denies smoking, chewing, dipping, or anything. 

I feel completely lied to and sort of helpless because I can't follow him to work with binoculars and watch his every move. I sort of have to take his word. But today was the last straw. I was making out with him and I noticed that he hesitated kissing me with his tongue and as soon as he did I tasted tobacco.
Now, people's mouth don't randomly taste like tobacco unless if they have been smoking. And he keeps standing his ground and saying that he has not been smoking. I tell him how disrespectful it is that he is lying to me and that I don't believe him because his mouth tastes like tobacco.

I'm asking for a nicotine/tobacco test. However would it work if let's say he only had a few huffs of a cigarette for just today? Or is it normal for people's mouth to taste like tobacco if they hang around other smokers? I've always given him the benefit of a doubt, but I feel like I'm going crazy. I want answers or someone else's opinion.
<bot>: boyfriend's mouth tastes and smells like tobacco sometimes after coming home from work. Says he isn't smoking or doing anything. I don't believe him but don't have evidence.