There are several dangers with these sites... Not the least of which is that the work you 'commission' will at best be 'samey' and of a poor standard, but may well also be recycled and possibly even stolen. - And make no mistake, it's the end-user who takes the first drop for this sort of thing, i.e. may ultimately find themselves at the doors of the High Court being sued for an IP infringement.
Placed in that position - how are you going to sue some fly-by-night? Or direct the IP owner to the guilty party? - And no, despite all the tripe that wafts around the internet, the 'big boy did it and ran away' excuse is no defence at all.
One important aspect of the work of a legitimate designer or other creative (of any kind) is that they will supply you, not only with the logo or whatever, but an audit trail for it. And that they will carry proper professional indemnity insurance should something go wrong in that respect. The work will (once you have paid for it) be licenced to you and only to you. - What's more it will be safe in terms of future development.
To the 'accountant types' advocating the use of these sites... How would you feel if some kid in 'Darkest Obscuria' was offering to audit people's company accounts, and complete their tax returns for £30? - Armed with little more than an ancient spreadsheet program, a 1970s pocket calculator and some scribbling pads; it's 'possible' to do - but is it possible to do it right? And, more importantly, is it possible to do it safely? Far away from the reach of any regulating authority or UK court, all the things you have to do to work in compliance with the law are merely overheads they don't have to bother their backsides with!
Rhetorically; what exactly is it we pay you Accountants for, beyond the superficial job of adding up and filling in forms? There's nothing more to the job that I can see! - Maybe I could get my fourteen year old niece to do that - she's good at arithmetic! So often, that's the mentality at play here.
The designer who expressed their outrage was quite correct in doing so!
It takes a minimum of 2400 formal (normally full-time over 2 years) study to obtain an HND in any given subject, double that to reach degree level... At which point you might just be at the stage where you know just enough about your chosen trade or profession to go out into the world and learn it properly by gaining some experience.
I'm often left laughing when I receive spam from these rogues galleries... They generally run along the lines of 'client wants corporate video made by a week next Tuesday, to include music, animation, voice-over, live action footage, editing - will pay up to £300!'
Aye, right... I'm going to load £30,000 worth of kit into a vehicle, drive half way across the country then spend a day filming some numpty who hasn't worked out what they want to say, run about like a blue-arsed fly organising music and graphics, deploy another £30K's worth of editing suite for another day, and roll all that up into a bundle for £300?
...Put it this way. My local Mechanic charges £50 per hour plus VAT. For that you get the benefit of his 40 years experience in the trade, all his tools and equipment, his lads are fully trained (HND in MVT etc) - and most of important of all, he's ACCOUNTABLE! - On the other hand, there is a local 'grease monkey', well known for dealing in stolen cars, drugs, been inside a few times, his lads are known burglars etc... Only £10 an hour labour, his advert proudly proclaims!
Who'll pay the ultimate price when one of the motors he cocks-up makes an effing-huge hole in the scenery?