What's there not to like? Actually, quite a lot. Since many salespeople have a 50/50 commission to base ratio or higher, it is quite important for the salesperson to get along with and value the work of the sales engineer. So I guess you have to be a likeable person.
More importantly, as an SE, you need to make the salesperson successful. Its also your commission, but with a ratio of 2:1 or more salespeople to SEs, sometimes you have to make more than 1 salesperson happy. This can also lead to competition for your valuable time, which in turn means you need to spend your time on the things that make you more successful.
This final idea is probably the most important point. If you are able to manage your own time effectively, you should spend most of your time on the things that will make the most money.
That $500,000 deal that you spent 6 months on? Less important than the $100,000 deal that just took a 2 hour demo.
The salesperson who made you do all the work on a doomed project? Less important than the other guy who wins every deal he goes into.
Once you are into making the right balanced decisions on where to spend your time, you will see something leading to my next post... that the Sales person will always want the best SE.