I think this reminder begs the question, "WHY is Hoary Redpoll considered a RARE regular?"  Is it due to few accepted records annually?  I think there are all kinds of reasons this species would not be frequently documented that have little to do with its rarity.  
First, identifying this species requires encountering numerous redpolls and having the chance to study many of them closely.  Thus, an observer traveling from the southern part of the state to the SaxZim Bog or Duluth for a Saturday of birding may have a low probability of chancing on a Hoary Redpoll and getting to observe it well enough to be confident with the identification.  Likewise, a birder from Duluth has the opportunity to view Varied Thrushes, Snowy Owls, Harlequin Ducks, Greater Black-backed Gulls, Golden-crowned Sparrows, and all kinds of reported and unreported birds of interest that likely reduce time spent studying redpoll flocks.  Conversely, in north-central Minnesota, redpolls in general are abundant, species--especially chasable listserv reports--competing for birding attention in winter are limited, and feeders provide opportunity for careful viewing.  In that context, while I don't frequently see beautiful, snow-whitish Hoary Redpolls around, birds that meet the field guide definition of a frostier redpoll with a mostly unstreaked rump and undertails, as well as the other subjective characteristics are not all that difficult to find with time spent.  So, for me, documenting a Hoary Redpoll in Itasca County seems like documenting a Black-backed Woodpecker in Itasca County....cool bird, but not front-page ornithological news.  
Second, considering that not all references agree and that with the exception of the most obvious Hoaries and Commons, redpoll field marks lie on a continuum, it's likely that many sightings would go undocumented because of lack of confidence.  A birder that sees an iffy female redpoll and identifies it as a Hoary because the bill appeared stubbier, the flank streaking was slightly finer, and the secondaries showed more white compared to Common is probably not going to submit documentation.  (Maybe I'm wrong, but I don't think so.)  This doesn't make the bird any less of a Hoary, it only means that Hoaries are almost certainly occurring in greater numbers than the aggregate observer bias involved in documentation would lead us to believe.  Even the field marks of such a bird, loaded with relative superlatives like "frostier, fluffier, stubbier" and hedging like 'may appear, averages, limited" lack the absolutes that encourage birders to document, especially when it is apparent that my idea of "frostier" or "faintly-streaked" is almost certainly different than that of each individual member of MOURC or even that of various field guide editors.  
My point is that I disagree with the notion that Hoary Redpoll is rare enough in Minnesota for observations of this species to warrant special treatment or the idea that any redpoll that doesn't look like a Snow Bunting in a red beret is either a Common or unidentifiable by birders who would otherwise claim to see the unbroken eye ring on a migrating Least Flycatcher.  Can I be the first to coin hornemanniphobia...fear of identifying Hoary Redpoll?   
By the way, for what it's worth I saw my first--and possibly second--Hoary Redpoll of 2009 on Saturday morning.  The account, which I shared locally, is below:
"Most interesting was a large flock of Common Redpolls feeding in a pair of small birch trees in Coleraine, oblivious to my presence.  One male Hoary Redpoll feeding near the top was easy to pick out as its frostiness, slightly-blushed breast, barely-streaked flanks, and unstreaked undertails were obvious.  A female was feeding very close to it, but the marks were not quite as clear, the undertails were only visible briefly, and this bird may have actually been a pale Common--though I think it was a Hoary."
Maybe I have this thing all wrong, but if I do, at least I'll take some of the heat off the photographers!  (And maybe I'll have to go back and erase Hoary Redpoll from my Itasca, Koochiching, Cass, St. Louis, and Cook lists!)  
Good birding.  
Shawn Conrad 
http://users.2z.net/itasca_chippewa_birding/  > Date: Sun, 18 Jan 2009 12:12:20 -0500> From: [log in to unmask]> Subject: [mou-net] **Hoary Redpoll** Reminder> To: [log in to unmask]> > There seem to be increasing numbers of Hoary Redpolls being reported recently, from several locations throughout the state. I would like to remind EVERYONE that this species is considered to have "rare regular" status in the state, and also presents an ID challenge, and therefore REQUIRES documentation. NO exceptions. I have been sending e-mails to individuals requesting documentation, but am getting a little behind, so please consider this message to be a heads up. Please know that to have your report published in the seasonal summary of this species in THE LOON, and included in the permanent record/ archive it MUST be documented. The preferred method would be to use the RQD form on the MOU web site. However, I will accept any contemporaneous notes or photos sent directly to me. ALL undocumented reports will merely be listed as such at the end of the introduction to the the Winter Season article when published.> > > > Any questions pertaining to this can be sent to me, Paul Budde (the Seasonal Report Editor) or Jim Mattsson, (Winter Season Compiler).> > > > > Thank you in advance for your cooperation.> > > > > Good birding!> > > > > Drew Smith> > Winter Season Compiler> > ----> Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net> Archives:http://lists.umn.edu/archives/mou-net.html
Windows Live™: Keep your life in sync. 
Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net