I'm interested in working in Bangkok for only a few months. Will it be easy to find something?
No. Most schools want you to commit to a one-year contract or 6 months at best. If you are here for a very short time, you will have more luck picking up work teaching kids or perhaps a 10-week corporate gig, where you teach at a company 2-4 nights a week for a couple of hours.
I used to get quite a few emails asking if it's possible to find work for 3-6 months. At present it probably is possible (due to a lack of decent teachers) but you'd be lucky to get enough hours to earn enough to break even. Schools want people who are reliable, will stick around and finish courses and will take the job relatively seriously.