I work freelance for my civvie job and accept them for that work so I know how easy it is, but having to report it on my taxes is something I'd like to avoid.

I'm not a tax consultant but I'd be worried about filing/receiving IRS 1099-K information forms.  According to the IRS, if the provider operates as a sole proprietor or independent contractor, and uses a third party (credit card, for example) to clear funds, then the provider has to issue a 1099-K form to each client who spent greater than US$600 with them in a calendar year.

These forms are tied to a social security number, or tax identification number for a business entity.

Cash is king for a reason

i take visa master ax and discover with discreet billing

I've accepted all 4 major credit cards for years, and never had an issue with it.  Almost nobody pays with cash anymore.

It's always billed discreetly, and I have never had an issue.

I believe my suitors find it to be much more convenient, time effective and safer than carrying a pocket full of bills.  It also means that there is no uncomfortable moment in handing over an envelope (as most choose to pay in advance).

I'm based in Vancouver/Canada though, and as per our tax laws, no tax forms are sent out to clients.  I simply declare all my income, and pay my own taxes.  

Receipts are issued for all transactions, via email, so discretion is  never broken.

I imagine trying to write off your liaisons could be problematic, so I wouldn't suggest it - thought I am sure it does happen.   I doubt any companion is going to falsify information if you get audited fro trying to write off your alternative relaxation methods ;-

credit cards

i use them all the time..perfectly safe..why clients have this ungodly fear of them is beyond me..