Yes, and Riley is allowed to get off scot-free while the blame for his exploites is laid at Buffy's feet by both himself and Xander.
However neither of them had sex with Darla or Drusilla before they were sired, therefore this example doesn't really fit.
Once again no sex takes place. They go to coffee, that's it.
Riley doesn't get off scot-free. He loses her. She does not have to accept his explanation that it is her fault and she doesn't. Xander points out the obvious: she is shutting people out of her life and if she wants Riley, she should go back and get him, otherwise, no need. It is revealed in As You Were 6ABB15 that it took him a year to get over her.
Faith in Who Are You 4ABB16 has sex with Riley and suffers no consequences other than what was intended - a good time with Riley and bad news for Buffy.
When Kennedy leaves the group being taught by Anya, Faith tells her that she can say, "I had him first" about Xander. Apparently no bad memories or consequences there.
In Chosen 7ABB22, Faith has sex with Wood and doesn't suffer any consequences other than having him say it didn't rock his world. Again, no disaster and the prospect is raised that it could continue.
In Gone 6ABB11, Buffy gets turned invisible by the Trio's ray gun and heads over to Spike's place and has sex with him (in fact, forces him to have sex and effectively rapes him). We see Spike doing pushups in bed, which are obviously (to us) sex but he tries to spin this as exercise. Again, no consequences other than two episodes later in Dead Things, she takes out her emotions again, violently, on Spike. Spike returns the favour in Seeing Red 6ABB19 but by this time, she has dumped him and that makes it attempted rape. You could consider this to be a consequence of her actions declaring this kind of behaviour to be acceptable, although there is no excuse for him to continue presing the attack when she objects. There is a dilemma - do you consider the AR to be a consequence of her previous actions or is it the wanton action of a demon with no regard for what came before? If it is a consequence, that would tend to let Spike off the hook. If not, then you can say her sexploits with Spike had no consequences.
In the Whedonverse, the sex act is not necessary to put someone in danger of bad consequences. Just expressing an interest is enough. In the Whedonverse, like politics, you should never waste a good crisis. Shock value is everything. Unexpected consequences are more desireable than instant karma.