user54321

forgive me if this is out there but I couldn't find it.
If a person is here on a b2 visa and does odd jobs like clean houses a few times, If they admit to that work do they lose their visa?

Anyway to answer OP’s question or to provide some context, people are having their long term B visas revoked at an unprecedented rate. I just happen to know because I researched it about two months ago and alerted my friends and family and even posted about it on a news portal popular in my home country. Just google visa revoked and search under news tab.
 
They are not only revoking visas upon arrival at USA airports, they’re actually calling people who previously had long term visas at home to come to the embassy and revoking for a variety of reasons including if they think you stayed a bit too long (not overstays) the last time, if you had a baby in the USA, etc. Some people actually got their visas revoked when they simply took their minor children to get visas for them. Of course it is within their absolute right to do so, no question however it’s bewildering.
 
As has been pointed out, even if your lady didn’t get a 5 year ban for expedited removal, it will be pointless for her to reapply for a nonimmigrant visa (except H1 etc which allow dual intent) probably for the next five years, or at the minimum until this current administration is out of power. They’re taking a real hardline approach to immigration, any hint or smell of a violation of visa terms and you get bounced. 

Is there a reason why most (not all) answers to the OPs question are so hostile, unsympathetic and judgmental? Wow! It’s like I can see some schadenfreude oozing out of people’s pores.
 
Or is OP the same person as @user12 who asked some somewhat strange obfuscating troll-like questions with a supercilious attitude? Because honestly the mockery and hostility is bewildering.

I know work is not allowed. but would they revoke visa for cleaning a few houses?

Another thing you should understand is CBP officers don’t need to have a factual cause or evidence to revoke a visa, all they need is suspicion of misuse to do it. They have been given these powers by congress as the gate keepers of the country. They also have powers to even detain and question U.S. citizens returning back home if they also suspect they have violated laws etc. A visa revolution is just a tip of what they can do.