Assuming this is about SEO; when in the decision making process, looking at keywords, and deciding which ones are worth building a site around broad should never be used for evaluating the traffic potential IMO.
The only time broad should be used is when you type the keyword into the search engines to analyze your top 10-20 competitors.
I base decisions to buy a domain and develop a site on exact match numbers. I often check phrase matched numbers if I want an idea of
potential traffic, but exact matched is the numbers for that exact phrase being searched. The value of phrase match shows you the number of searches that include your keywords in a specific order. So if your keyword is [blue widgets], then buy blue widgets, blue widgets reviews, blue widgets scam, etc are part of your potential traffic.
since you can do blue widgets, widgets blue are basically the same and in general if you move the words around it should still remain targeted.
Not exactly. If blue widgets gets 5400 exact searches and widgets blue gets 800, then it's an easy decision which one to build a site around. Also, widgets blue may rank for stuff like "green widgets with blue sparkles" or even "big widgets blue balls."
Try taking a look at the SERPs for widgets blue as well. If there are alot of advertisers on the page for blue widgets but few for widgets blue, that will also give you a clue to not waste too much time on that keyword.
EDIT: just saw your edit, lol. The "+" is a whole other can of worms, and you should pick the keywords you want to target based on the basic words. You can't depend on search modifiers that most people probably don't know how to use.
Also my post is verbose and may not make much sense. I'm suffering from gone to the dentist today and taking prescription narcotics and drinking beer fogginess, lol.