It is tricky to discuss one's experience as a confessor, lest it lead to inadvertent breaking of the seal of the confessional. However, let me just say that the challenge, as I see it, is not the particular sins confessed. Most confessions, I would imagine, involve the confession of mundane sins of the sort that everyone commits on a regular basis, and in this day and age, particularly in the ISM context, everyone who comes to confession is sincerely penitent. Most confessors, upon hearing the list of sins, will most likely think, "Oh, yes, I committed this sin just the other day. Yes, that is an area I need to work on as well." Giving a penance (and I have only given the reading/praying of Scripture -- mostly the Psalms -- as a penance) and giving absolution is not really the challenge.
The real challenge is meeting the penitent where they are in their spiritual life and helping them. Some penitents come because confession is a regular part of their spiritual lives, and they are really only seeking absolution. And that is okay -- that may only be there to receive the sacrament. Others, in addition to this, may come to the sacrament also seeking a way to deepen their spiritual journey, and the confessor ideally will be able to hear this and provide some counsel or advice that will help the person to take the next step, whatever that may, on that journey. And since people are coming from a variety of places along that journey, this can be a challenge.
It's really no different at all from ministering to the people who come to Mass. The priest's duty as preacher and celebrant of the Mass is to preach the Word of God well and to celebrate the sacrament in a reverent and prayerful way, so that all who attend may receive the Word and the Body and Blood of Christ to strengthen them for service in the world. However, there are those who will come with a particular spiritual need, and before or after Mass, the priest may be called upon to provide further pastoral care to help that person where they are. Again, that can be a real challenge -- in fact, that may be a much bigger challenge, since it comes in the context of interacting with a whole community, and it can be trickier to discern the signs of what is going on with a person.
Discussing the interesting hard cases of the really big sins, or the preaching of particularly difficult texts, or the precise rubrics of the Mass are fun exercises -- it is dealing pastorally with individuals and communities that is the difficult work, and it is an art, not a science -- and the grace of the Holy Spirit in the moment often proves much more valuable than all the conversation about it in the world.