Is recommending a particular shop, online shop, or brand when answering a question acceptable, or would it be considered advertising?
I think this actually breaks into two different issues.
Discussing a particular brand can be helpful, as long as the qualities or characteristics are relevant to the question that was asked.
- I have found that SuperFun yarn does not felt well, but WowFelting yarn is easier to work with.
- You don't have to buy HighPrice glue for this project, just dilute everyday white craft glue to get the same result.
- Different crayon brands melt differently, and the results from ThisFamiliar brand are more consistent than generic crayons.
If I'm trying to figure out why my project isn't working as well as expected, sometimes it is about the quality of the materials I'm using.
Recommending a particular store, even online, is less useful for two reasons.
Firstly, not all users will have access to it. My local fiber arts store isn't available to anybody but me and my neighbors. Even a national chain won't help people in a different country. Even an online store may have policies about shipping internationally. So being told that somebody can find supplies at MegaCraftEmporium doesn't help me if there isn't one near me.
Secondly, aside from whether a store has a particular item in stock, a suggestion to shop there doesn't have much bearing on Arts & Crafts. It's great to know that MegaCraftEmporium is friendly, often has sales, and its sales associates are knowledgeable and can recommend different products -- but that's more of something that would belong in a chat room context than in an Answer.
I'd say mentioning the brand you're currently using when asking a question makes sense, as it may give the experts an idea of whether or not the quality of your materials is a factor in the results you're getting (or not getting).
When answering, I think it makes more sense to specify the type of material/product that would work better, and then clarify that with a brand of product if necessary.
For instance, if you need to explain that someone should use a firmer polymer clay to get better results when caning, you might mention that Kato products are an example. Then users have a point of comparison in their search for suitable product.
I can't see there being a need to reference where to buy something. "Available online" or "you should be able to get it in major craft stores" should work. Or even "search for this phrase: xxx and you'll find places that sell it." There shouldn't be a need to say "You can buy it from Joe's Craft Shack."
Sometimes brand makes a difference. So if someone is looking for a specific feature or effect, one brand could very well produce that much better than another one.
This can be in an answer too.
Q:"I want my forehead to be shiny with sparkles, how do I go about it?" (ignore the question is too broad)
A: "Well I've tried Goblin Snot Gel and while it gives a good shine at first and has some sun-screen capabilities, it has no sparkles and after 24 hours dries kind of crusty, however, Unicorn Poo Gel doesn't have quite the shine, it does have plenty of sparkles and still looks the same after a hard night of partying..."
Though I would expect it to make more of a difference in the question. And I rarely see a reason to have a store or retailer named, unless they are the sole provider of a specific product.
Would you consider recommending a particular shop/online shop/brand when answering a question acceptable?
I think you should generalize to a product category whenever possible. There is nothing really wrong with brand recommendations as long as that is not the sole focus of the answer.
So if the topic was glues, for example, your answer could be to use PVA glues and you could suggest using Titebond. There easily could be exceptions as Arts & Crafts will be very broad as far as categories but you should try to avoid them if possible.
Or would it be considered advertising?
If you do have any affiliation with the product then that should be disclosed in your answers. Going overboard with brand suggestions could be flagged as spam.
If questions are asking for brand recommendations we should consider editing the question to make it more generalized or close it as too opinionated.
Brands can matter, especially when it comes to many of the visual arts such as painting or drawing. For example, Faber-Castell Polychromos pencils are professional-grade pencils with high lightfast ratings and are not in the same league as Crayola pencil crayons for kids. Depending on the question, this can matter quite a bit.
So, really, the context matters here. While I generally consider product/service questions to be off topic, this site is, I think, going to attract questions that will lead to brand specific recommendations and I think we're going to need to respond to those on an individual basis rather than have a standard response.