I'm sure it's possible since they technically own the logo and are a legit business they may copyright it. Hence leaving you in the section of copyright infringement if you use it,
Actually, that's wrong. It's copyright infringement IF you use the logo as a brand for yourself. If you are the designer , then the image of the logo isnt being used as a logo but as a sample of your work as is thus perfectly legal to present. The only exception is if you agree to do "white box" work.. but I will touch on that in a second.
It even completely withing your legal right to do re-brandings of well-known companies, as proof of concept, and place/show them them (strictly) in your portfolio.
The client doesn't need to build the portfolio, you do.
Designers don't need clients t build portfolios. A portfolio is a sample of you creative achievements not a list of bedfellows ( tho doping names is nice, but any name-worthy company doesnt accept 'volunteered work', so that's not areal option either)
* Many GREAT designers don't even show the logo the client bought, as clients often have poor taste or give poor directions. Some show several design options ( with a an optional highlight for the clients final choice). This serves to show case the designer creative process and not who your previous clients have been. It also serves to mitigate bad client choices.
I have a horror story in which I created a slick minimalist logo for a bottled water distributor. Originally it was a minimalist 2 drops of water and the company name. During the design process , the client insisted that a figure "about to drinking the water be added". This really reduced the punch and versatility of the brand mark , but , hey it was 'his' logo. The horrible part was for the silhouetted 2 color versions. The client insisted no having the drops be yellow since "blue is a sad color" ( that was exactly his argument for 4 days , before I conceded just to get the project finished.. again it was 'his' logo. So yes , his brand for drinking water consists of a cartoonish figure letting 2 piss yellow colored drops fall into its mouth. Needless to say that project doesnt grace my portfolio. in short, clients DO NOT equal portfolio pieces.
Why would you want to show off a bunch of un-used designs?
Because what you need to show is design that attracts (good) attention. Your best designs, used or not. To a prospective PAYING client ( and that what you ultimately want to be able to have paying clients and profit from your talents) it really doesnt matter much if your last 15 logos were used by someone as much as if the logos in your portfolio are STUNNING in CONCEPT, DESIGN and EXECUTION!!!
Also remember that mediocre logos dilute the impact of your portfolio. So if you had 5 stunning logos. and 10 mediocre ones that came out of client interactions (paid or not) , you really have a portfolio that is only a third as strong. Either way you could build a great portfolio with or w/o clients.. that is unless you are not creative enough to give yourself assignments.
Another thing: I am NOT condoning this and remember that consequence would be dire if you are found out but for the sake of example: a designer could 'steal' 10 (obviously not high profile) logos that are in use somewhere and claim them as their own.. the reason for this is that prospect dont/cant check references ..."hey did so and so create your logo back in 2005?" and worse still former clients other than maybe sending you a "blurb" for your testimonials will not field dozen of calls per month vouching for you and your work even if ( or especially if) you did free work for them. So, again, the only thing you gain is a placebo effect for your confidence.
Yet another issue is that you may end up setting a business precedence. "you are the free logo guy". Trust me, once that gets establish it will be difficult if not impossible to merely say ... "I was but now am the $65/hr logo guy." "oh", you say, "but my prospects wont tell others that I did this for free"... the truth is that the first thing they will say. People are self-centric and life is all about THEM: if your work is mediocre it excuses them , if your work is outstanding it show cases how savvy they are that they got such excellent work for nothing or nearly nothing. Your clients are in bussiness for themselves and not there to serve as your agents and publicists.
Yet another side effect of the same behaviour is that you CAN do outstanding work, but nothing beats "free". So the quality of your work will be overshadowed by its price , and your strategy will backfire.
The only thing 'donated' logos serves to show is that you have worked with others, that's it. And, without a testimonial, that doesnt even serve to say whether you worked well with others or not.. just merely that you did. Tho it may not apply directly to having a business, some clients will discard 'free work experience' altogether. Like when an agency reviews/declines a good portfolio, based on 'no REAL agency experience'
Ok, I promised I would elaborate on this. There is a term: "white box". This means you do the work but AGREE before hand not to take the credit ( kinda like ghost writing, only worse). But in order for that to be legally binding you have to know you are accepting "white box" before hand. Honestly, anyhow, I would avoid white-box work that doesnt come with AT LEAST 5 figure compensation.
In short don't forget YOU ARE BUSINESS TOO! The TRUE goal of a business is not just to have a clientele but to have profitable transactions.
One last aside:
As in building off of free work, how do you think Nike got their logo? Someone did it for free, then as a thank you they gave the designer stock.
The stock was how the designer was compensated. Not all pay will be cash. Batter works, sometimes too.
All am saying is that the ROI on 'free work' is not the best path. If you cant apply it to other business models it it shouldn't be for you either. For fun , the next time a 'new and un established' restaurant opens in your town go there tell them you want to eat for free, but that you will let THEM tell people you came there to eat and that maybe some of those people will like the food enough to chose to pay... eventually.