Yes, bots are beatable. A bot is only as good as its program and it takes a lot of work & knowledge of writing code to program a successful bot. But even the most successful bot is barely above the break even line. Also, a lot of the bot's style of play comes directly from the the programmer's knowledge of the game and how he himself would play. Since every bot is simply an extension of its maker, it's nearly impossible to give a general list of 'tells'. Most bots, however, are programmed to play fairly tight, quality hands and when reaching a specific point, like say 10 times the big blind, will push with even a moderate hand. They can also be programmed to steal the blinds randomly.
In summation, just play your game, learn & improve your game and you won't have to worry about a bots tells
. Remember, a bot will never tilt and a bot will never chat, unless its programmer is watching it play and chats for it or overrides its play.