What kind of sale is it? If it's a registered sale, I would get them clipped like you are going to a show.
Torching (propane torch) them doesn't look real good on Herefords, you can do it, just don't torch the white. You can burn down the tops and shoulders, but hitting any white makes them look yellowed.
On black cattle, thats all I pretty much do any more. It saves a bunch of time and if you take care when doing it, they look better than ones that are clipped. That's not even slicking them down with the torch. Actually works good on all cattle except those that are red and white. I've done alot of sales and never have figured out how to get the Herefords done real nice with a torch. Usually just clip the cheeks, brisket, trim up the neck and topline then burn the tops and shoulders.
I wouldn't slick sheer anything unless it is in the summer. Slicking any other time of year looks like crap. Also any cold temps can make them real sick.