Played by Jim Pirri, Agent Scardino was introduced as a love interest for Lois. The fans, though, wanted Lois and Clark to see only each other. They rejected Mayson Drake (Farrah Forke) who fell for Clark and they hated Dan Scardino.
The agent first appeared in the second season episode "Resurrection", written by Gene Miller and Karen Kavner. One of the reasons he was so despised is that episode closely followed Lois and Clark's first date and first "real" kiss. Seeing someone go for Lois at this time greatly increased the possibility for animosity. Admittedly, Scardino comes across as, for want of a better word, "greasy" in this episode, and it is easy to dislike him. Later, though, he becomes a wonderful character.
You see, part of my support for the character of Scardino comes from my view of him as a necessary plot point. Clark needed the jealousy to get him going. Many people overlook this, but I wonder if the couple would have gotten where they are today if it hadn't been for the intervention of this one man. But I digress...
When he reappeared in "Target: Jimmy Olsen" (written by Tony Blake and Paul Jackson), Scardino seems much more caring. He thinks he would be good for Lois and he is trying to protect her. This is really when I warmed up to Scardino. In this episode, a girl called (I think) Sarah Goodwin advises Lois to go for Dan rather than Clark, saying that Clark is like chocolate ice-cream, and Dan like rocky road. She says that chocolate is good, but you wouldn't want to only be able to eat it for the rest of your life because it's boring. She says to try rocky road; chocolate will always be there. To this, Lois replies something like: "Not necessarily. I think I'd really miss chocolate if I couldn't have it any more." With this one line, Scardino's entire existence is justified. Although she is still torn at the moment, this is the beginning of Lois' realisation that she will spend the rest of her life with Clark. It is a necessary first step that might not have occurred had Scardino not sparked the jealousy.
Also, in this episode, Lois decides at the end to ask Dan out for a date, because Clark is running out on her every time something to do with their relationship comes up. Of course, he is off to save someone as Superman but she doesn't know this and in her place, Clark would seem to be very unsympathetic and even rude. I think it was the right thing for Lois to do in this situation, even though we all want her to end up with Clark. Still, most people cheered when Jimmy knocked Dan down the stairs...
I believe Scardino was mentioned in "Individual Responsibility" (written by Chris Ruppenthal and Grant Rosenberg) but didn't appear. Flowers and gifts arrive for Lois from Dan (who's away on a case) and Clark gets more and more afraid of the threat of competition. He takes the opportunity presented by Scardino's absence and asks Lois again to reconsider going out with him on a second date.
The last episode in which he appears is called "Whine, Whine, Whine" and was written by Kathy McCormick and John McNamara. Lois is frustrated by Clark's constant running away (of course we know it's to save people but she thinks he is insecure or something) and leaves him a note that reads: "Forget it!" Lois sees a psychiatrist about who to pursue a relationship with: Clark Kent, Dan Scardino or Superman.
Also in this episode, Dan has to pretend to be a crooked FDA agent, and Lois finds out but thinks he really is one and that he's been lying to her. I'm sure many people wanted her to stay with this delusion, but it would be unfair to Dan (who has done nothing wrong) and the writers realized this. Lois discovers that he is just working under cover and ... well, there are some interesting moments in it but I can't remember the exact plot so I won't embarass myself by trying to discuss that part of it.
So there you have it: Dan Scardino, all round nice, but often misunderstood and at times hated, guy. I like him, you don't have to. But please, don't let the desire for Lois and Clark to get together manifest itself as hatred of Dan Scardino. I think we're all better people than that.
By the way, Jim Pirri currently plays Jack Pappas in the endangered series "Union Square". Watch it so it won't get cancelled!
Most of the information within this passage was acquired from Metropolis Place.