I have seen quite a few people around PMC offering to make skins for people, free of charge. Sometimes they will ask you to subscribe if you want your skin higher up on the list. This is what I'm saying though, I have seen at least 5 people or so that are popular skinners, and they will say "I suggest you don't do skin requests, it will ruin your rep." or something like that. Now personally, I think that this could be true, but not so drastic as too ruin you for life. And here is why.

Pros.
1. It can rake in exp quicker.
2. It can increase your popularity, too some extent.
3. If you offer subscriptions to make them higher on the production list, that could help.

Cons.
1. It makes you seem like you have nothing better to do
2. People can give you a bad image if they hate your skins. ( Their rages will be shown to the public )
3. It kinda shows that people aren't willing enough to like your skins unless you make EXACTLY what they want.
4. You will have a large list of subscribers that really want nothing to do with you. ( Most of them anyways )
5. You'll seem kind of desperate for attention.

Random:
1. If you are going to do this, do not be stupid and do skins on things like unicorns.

So the pros and cons kinda, but not really, weigh out. I still don't think it will ruin everything though. Personally, I have nothing against people who do skin requests, I actually like them for doing my requests for me. Just take what I have said into consideration next time you think about making a skin shop.