I've been filing it as a Schedule C income for several years and paying SE taxes. I deduct some expenses each year but not a lot, definitely not enough to offset the SE taxes I have to pay. Are there any risks associated with filing it as a hobby income, like a higher risk of getting audited especially after doing it for several years?
I can't think of any reason i would call this a hobby (at least in my case). I mean I like the extra money but if i stopped getting paid for it, i would stop doing it immediately and never miss anything about it.
Yeah, I don't have a lot of expenses either. I do any CC annual fees on cards which I've sold slots that year - I don't think there are many of those. I do my Quicken subscription fee, because I need Quicken to keep track of my many credit cards - closing dates, limits, balances, charges, payments - in order to maintain the quality of my cards to be able to sell slots. I do a small percentage of my cell phone and Internet bill, since I use those in the course of selling TLs.
Audit risk is hard to quantify. First, not that many returns get audited - less than 1% I think. Second, most returns that get audited are high income, high charitable deductions, or areas that are rife with fraud such as EITC or CTC. So if you got audited, it would probably be a very low probability sort of thing where you got chosen to be audited just at random and not because you chose to report a 1099 as hobby income over several years.
If they did a full audit (which is even more rare I think), then they'd probably ask you to explain why you chose to report it as a hobby rather than a business. At which point a well-prepared taxpayer would have a rationale based on the IRS' hobby-or-business link I posted earlier.
The IRS could then say, no, it's really a business and we're redoing it as a Schedule C and billing you accordingly. At that point, you'd be within your rights to include any business expenses as deductions to help offset a bit. You'd owe the additional SE taxes, with interest, but almost certainly no penalty. I think it's unlikely the IRS would then choose to go to your other years' returns to catch the same issue. They could but I think it wouldn't be worth their time even if they had you right in front of them.
All that being said, everyone should prepare their taxes accurately and honestly and pay what they owe.
As to your last paragraph, yeah, I'm pretty sure "profit motive" is one of the listed characteristics that tends to point to it being a business. And to me, it's one of the more important characteristics in terms of defining the tax treatment of the income.