So the interesting thing about bitcoin is that it costs money to receive bitcoin. This is because eventually you are going to need to spend the money, and it's a lot cheaper to send a single 10 BTC output, than ten 1 BTC ones. For an un-optimized wallet (like 99% out there...) this is actually fairly expensive.
So what some casinos do is impose a min deposit, while others will ban accounts that make too many tiny deposits (e.g. from faucets). This is pretty suboptimal, because a user shouldn't really need to have to worry about what the min deposit amount is, or what is "abuse" or not.
But what is by far the best way to handle it, is what bustabit/bustadice do. There's no min deposit amount and you can never get banned from making too many small deposits. Instead what they do is each time you deposit create a tiny debt ("unpaid deposit fee") which is currently almost nothin (93 satoshis) which represents the cost for them to economically consolidate the inputs. When ever you want to withdraw, this fee is tacked onto the cost of a withdrawal. It's pretty much the perfect system for both the site and users.
This is actually how a few years back a bitcoin exchange called Bitfinex got a spam attack. There were spammer making basically hundreds or thousands of tiny deposits into account and it created an issue when the exchange wanted to spend those outputs to process withdraws for customers. It basically lead to them charging for deposit which got really annoying. If you depositted less than $1000 in crypto equivalent they charged you something like $5. No idea if they still charge for deposits, however this was the only exchange I know that did that.
Most bitcoin casinos don't really have minimums, unless you are trying to deposit something small like a penny and hence it doesn't make sense. If you really only have like $5 to gamble with, you are betting off buying some alt-coin like Doge and using that. Usually the min deposit will be much less than BTC and you won't run into any issues.
Hence if you are gambling with $5, you might as well just gamble with faucet. Won't ever get rich that way anyway.
Just an example. 
