Why straight come to guys

Hey thereSo i have a question what is it with "straight" Guys..especially married guys posting on sites like Craigslist they want a bj,hj or anal...I mean i get that you can go through a dry spell but doesnt this seem to go against the "Straight "LabelAnd for thay matter why post that you are looking to suck or fuck a married guy? Is there some thrill that goes with the conquest or something ?