If you are talking about people asking you to write a sample for free, I get it. I would not. But it is industry standard to provide writing samples. I find my samples seal the deal most of the time, or at the least let the client know what to expect from my style and tone up front. Can I supply samples for every conceivable niche I write in? Of course not. So, I use a quick response, give the sample link, and explain how my work helped that client and what the goal was. Not giving samples, IMO, makes you a stubborn seller, and I would see why buyers would gloss you over. In such a competitive place, you have to prove yourself. Sample help show why you stand out. Otherwise, you are just another face in the crowd asking for a handout. Why give you the job when some other strange unknown quantity will give it for cheaper. The nature of this marketplace is competition. I understand you feel tired of doing this every time, and it must be exhausting to refuse people and explain why every time! And people have a general trust worthiness we do not give them credit for. Many look for work with out bylines. While others understand we ghost write. And if you are pointing someone to a url with the work on your previous clients site, it should be ok by that client. Clients usually tell me when not to use their work in my portfolio. And I always point to the website the work is on… never just a word document with sample as a watermark. I think you are missing a HUGE opportunity to sell yourself.