It’s not that difficult but it’s also not recommended.  You risk being fined/deported, as well you have virtually no rights when working illegally (so if you’re ‘employer’ decides to shaft you, there’s no recourse you can take).
 
Better get a trade & find something above-board if working in Europe is your goal

how would a person even go about finding under the table work? i mean who would you approach and what would you say?

not the goal….just a thought for now.

Maybe hang around hostels a lot.  They sometimes like to have multi-national employees, and its easy to just ask whoever is working if the boss is looking to hire or needs any extra help.  Its not very likely, but there are so many hostels that you might eventually find something. 

why are you looking for underground work in Europe? Are you running from the law? If so I’ve got some under-the-table work here in Canada if you interested

haha no thanks.  i think i have things sorted out.

Or I could give you a job under the table, if you’re the thirsty type

normally this is when i’d post a “look of shock” face….but that could be taken one of two ways…..

less’ be easy

i hope im not breaking a moment for two here….
 
but with regards to the question – if you do that in Spain its quite easy. In fact, in some places (like valencia) most work means under the table work. It’s much easier to find that than legal work. Laws are there but as usual… who cares?

If your country is a member of the Commonwealth which I believe it is, you will have no problem working in the UK for 2 years. They provide a temporary working permit.
Finding work in restaurants and other import-export houses with no visa is quite common in UK.
 
If you are considering to work in Uk and need a place to stay in London, let me know. I will be there shortly as the current tenant is leaving shortly.
You can write to me at [email=spmohanty@aol.com]spmohanty@aol.com[/email] or call at 973 248 8503.

Is a work visa required for all “legit” work or are there loop holes in certain areas? If I were to just show up in, oh say London, around August and start looking for jobs, would I be totally screwed as a US citizen? I don’t mind doing “under the table” work, but wouldn’t mind having a little more security, and I’m finding that it takes money (aka paying for a TEFL or something similar) to get the legit work.

i think working in the UK is probably the most logical solution for me. (i already speak the language)

i’m not sure when i’ll be landing in the UK, but i will send you a message when i have the dates set.