I'm far from the most qualified to answer this, however I'll give it a go.

Arbitrage bets are REASONABLY infrequent, and normally aren't too profitable.

I'd think the sport has alot to do with it (local or int.). I'd think boxing and tennis would have arbing opportunites.

I have also heard arbing is most advantageous with bonuses (online). As there are many online books, I'm sure the opportunities are there, you just have to look for them.

They may be reasonably risk free (good for a small BR, and combined with bonuses&shopping could make decent profits), however they become less profitable the larger your BR becomes.

If anyone would like to elaborate or dismiss what I said, feel free to do so. Again, I'm pretty inexperienced at SB.