I can't do it. I strongly recommend one pro-product that will benefit them the most, explain why it's worth the money, give them a sample of the second most important and recommend they start budgeting for their skin. Most pro products requires less; I advise them to be stingy with the product and let them know it performs better and will last just as long if they treat the product like gold. Many clients of mine will not purchase pro-skincare. I love on them anyway but I'm honest. Favorable results are similar to what you eat shows on your body and what you put on your skin shows on your skin.
Yesterday I had a client who works for Estee Lauder and I recommended Amlactin for her son's back. Normally I don't but I had a client who experienced improvement with some weird dryness with Amlactin.
One area of OTC I believe in is sunscreens. Getting people to use sunscreen is hard enough, without asking them to invest a pretty penny, I would rather they have a better cleanser or moisturizer.
Sunscreens have such wide variances - physical vs chemical, different SPF's, lotion, cream, powder etc it would be impossible for me to keep something on the shelf that appeals to everyone. I've found some I like that I use myself (I am allergic to MIT so it cuts out a lot). I prefer pro-brands, but there have been some that don't feel as nice as what I get OTC - and there is the same ingredient mix. Takes a lot of homework, but I'm able to recommend something based on interviewing the client and have it at their fingertips in the grocery store.
We all have our own philosophies, but I tend to work in the direction of client compliance, rather than the sale. Building that trust brings them in the next time.....